Please do not destroy or throw away this publication. If you have no further use 

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UNITED STATES DEPARTMENT OF THE INTERIOR 

Ray Lyman Wilbur, Secretary 

GEOLOGICAL SURVEY 

W. C. MendenhaU, Director 

Professional Paper 175 -C 

REPLACEMENT ORIGIN OF THE ALBITE GRANITE 

NEAR SPARTA, OREGON 

BY 

JAMES GILLULY 

Shorter contributions to general geology, 1932-33 

(Pages 65-81) 

UNITED STATES 

GOVERNMENT PRINTING OFFICE 

WASHINGTON : 1933 

For sale by the Superintendent of Documents, Washington, D. C. Price 5 cents 
CONTENTS 

.Abstract ________________________ ____ ___ _______ ___ _ 

Introduction ____ :.. __________ ___ _______________ _ 

Sketch of general geology ____ _____ ________ _____ ____ _ 

Diorite and quartz diorite ___________________ _______ _ Distribution ___________________________ _______ _ 

Lithology ____________ ____ ___ _______ __________ _ 

Albite granite ___________________ __ ________ __ _____ _ 

Distribution ____ ____________ ________ ___ ______ _ _ 

Lithology ______ ____ ___ ___ ________ _______ _____ _ 

Megascopic features ____ _ -------- ------------ Microscopic features ________ ___ ___ _____ __ _ 

Texture -- -- ---- --- -- -------- -- ---- Grani tic texture _____ ____ __ __ ___ __ _ 

Micrographic texture _____ __ ___ ____ _ 

Myrmekitic texture ____ ___________ _ 

Cataclastic texture _____ _____ ______ _ 

Crystalloblastic texture ________ ____ _ 

Mineralogy and mineral habits ____ _____ _ 

Plagioclase _____________ __ _______ _ _ 

Quartz ___ ___ __ ___ _______ ____ ____ _ 

Amphibole ____ ___ ______ ____ ______ ·_ 

Biotite ______ ___________ ________ _ _ 

Sericite ______ __ ________ _________ _ _ 

Epidote ____ __ __________ ____ ______ _ 

Subordinate minerals ____________ __ _ 

P age 

65 Zone gradational between quartz diorite and albite 

65 granite ________________ __ _______ _______________ _ 

65 Field relations ______ __________ ________________ _ 

67 Lithology _____________ _______________________ _ 

67 Chemical features ______ _______________________ ____ _ 

67 Conclusions respecting relationship ___________ ""' ______ _ 

67 Evidence of late magmatic or hydrothermal· mineral for67 mation _____ ________________ _____ .:. ______________ _ 

67 Textural evidence _______ _____ ___________________ . 

67 Mineralogic evidence __ ________________ ~ ________ _ 

68 Summary of microscopic evidence _______________ _ 

68 Evidence of the variation diagram ____________ ___ ___ _ 

68 Source of the albitizing solutions ______ _____ _________ _ 

68 Solutions derived from the solid diorite by metamor68 phism ___ _ .. _____________________________ __ _ _ 

68 Solutions derived from the intruded greenstones __ _ 

68 Local rest-magma solutions _____________ __ _____ _ 

68 Hydrothermal solutions of deep-seated origin _____ _ 

68 Selective enrichment of soda in hydrothermal solutions_ 

69 Albitization in other granitic rocks __________________ _ 

69 Other albite granites _______ ...: ________________ .. _____ _ 

69 Field associations __ ___________ __ __________ :.. ___ _ 

69 Mineralogic and textural features ______ _________ _ 

69 Conclusion _______________ ___________________ _____ _ 

69 Acknowledgments ___ ;. ______________ ____________ __ _ 

Page 

69 

69 

69 

70 

70 

71 

71 

73 

74 

74 

76 

76 

76 

77 

77 

77 

78 

79 

79 

80 

81 

81 

ILLUSTRATIONS 

PLATE 19. A, Albite crystal embayed by quartz ·in 

structure interpreted as due to replacement; B, Micrographic texture of albite 

granite; C, "Brain-coral" myrmekite in 

albite granite; D, Cataclastic albite granite 

20. A, Cataclastic albite granite; B, Crystalloblastic albite granite; C, D, Albite granite 

21. A, Albite surrounded by micrographic rosette 

of albite and quartz; B, Enlarged photograph of border of micrographic intergrowth 

against the central albite crystal; C, 

Enlarged outer fringe of micrographic intergrowth shown in A; D, Graphic intergrowth of albite and quartz showing some 

resemblance to myrmekite ______________ _ 

22. A, Albite, showing tendency toward chessboard structure; B, Albite granite cut by 

veinlets of clear albite; C, Wisps of residual . 

albite in quartz which is replacing it; D, 

Albite crystal partly replaced by quartz in 

pseudographic structure ________________ _ 

:II 

Page 

PLATE 23. A, Albite being replaced by quartz; B, 

Sericitic albite coated and veined by clear 

albite; C, Albite partly replaced by quartz 

in crude graphic structure; D, Central core 

68 of somewhat sal.issuritic andesine.· surrounded by albite in relation interpreted to 

Page 

68 signify replacement_____________________ 68 

FIGURE 1. Sketch map showing general geology of parts 

of the ·Baker and Pine quadrangles and 

distribution of intrusive rocks_~---------- 66 

2. Variation _diagram showing chemical composition of quartz diorite and albite granite, 

contrasted with the weighted variation 

diagram of the Katmai rocks and a varia68 tion diagram constructed from the analyses 

of the opdalite-trondhjemite series________ • 75 

68 
REPLACEMENT ORIGIN OF THE ALBITE GRANITE NEAR SPARTA, OREGON 

. By JAMES GILLULY 

ABSTRACT 

The albite granite near Sparta, in the foothills of the Wallowa 

Mountains of eastern Oregon, is thought to be a product of 

albitization and partial silicification of an earlier' quartz diorite. 

These changes· are attributed to late magmatic and postmagmatic replacement of the almost completely solidified 

quartz diorite by solutions derived probably through filter 

pressing from lower portions of the same mass. These solutions 

were guided, at least in part and probably entirely, by brecciated 

zones in the quartz diorite. 

Mineralogic changes effected were the replacement of the 

andesine and subordinate orthoclase of the quartz diorite by 

albite, the replacement of some of the common green hornblende by the soda amphibole, hastingsite, and the introduction 

of large quantities of dark-blue quartz. This quartz is decidedly 

different in habit from that of normal granites in that it occurs 

in irregular nests and veinlets penetrating the rock in many 

directions. Most of the dark minerals have been removed. , 

Myrmekite and micrographic textures are common in the albite 

granite, though absent from the unaffected quartz diorite. 

That the albitization and other changes of the albite granite 

have resulted from later reactions on the quartz diorite is shown 

by field relations, microscopic study, and chemical analyses. 

The process is considered analogous to that of large-scale 

pegmatitizatiori. 

The rocks are all of presumable Mesozoic age. 

Many albite granites elsewhere are characterized by features 

like those found in the Sparta rocks. These include common 

association with crushing phenomena, widespread occurrence of 

graphic textures, of epidote and other low-temperature and 

hydrous mafic minerals, and of milky and rutilated quartz, and 

unusual amounts of replacement. Although the findings of the 

writer with respect to the Sparta rocks are in agreement with 

the thesis of Bowen that albite granites are of hydrothermal 

origin, it does not appear that a survey of the world literature 

on such rocks is at all conclusive on the matter. 

INTRODUCTION 

In connection with a study of the mineral deposits of 

eastern Oregon 1 the geology of the Baker quadrangle 

and portions of the Pine quadrangle was mapped by 

the writer and his assistants during 1929 and 1930. In 

the course of this work opportunity was afforded to 

study in some detail the soda granite near Sparta, 

briefly described by Lindgren/ together with the diorite and quartz diorite closely associated with it and the 

gabbroic rocks associated with similar albite granites 

elsewhere in the general region. Owing to the unusual 

composition of the rocks and their intimate association 

with the diorites and gabbros some time was spent in 

1 Gilluly, James, Copper deposits near Keating, Oreg.: U.S. Geol. Survey Bull 

830, pp. 1-32, 1932. Gilluly, James, Reed, J. C., and Park, C. F., jr., Some mining 

districts of eastern Oregon (in preparation). 

2 Lindgren, Waldemar, The gold belt of the Blue Mountains of Oregon: U. S. 

Oeol. Survey Twenty-second Ann. Rept., pt. 2, pp. 585-586, 732, 734, 1901. 

studying their field relations. During this work and 

subsequent office studies the writer was led to the 

following hypothesis to explain the origin of these 

interesting rocks: 

. The albite granite is the product of albitization and 

partial silicification of portions of the gabbro, diorite, 

and quartz diorite. These changes are the result of the 

late magmatic and postmagmatic replacement of 

almost or quite completely solidified diorite. The 

replacement was brought about by circulating solutions or extremely hydrous rest-magmas derived from 

deeper levels in the mas'5, in part at least by "filter 

pressing" and in large part guided by brecciated 

zones in the diorite. 

SKETCH OF GENERAL GEOLOGY 

The dominant geologic units of the northern part of 

the Baker quadrangle ·and the northwestern part of 

the Pine quadrangle are (1) a series of altered lavas 

and pyroclastic rocks, with subordinate limestones, of 

Permian age; (2) a group of plutonic masses including 

gabbro, diorite, quartz diorite, and albite granite, 

of post-Permian, pre-Tertiary age, intruding these old 

volcanic rocks; (3) a series of Tertiary lava flows and 

associated fluviatile and lacustrine sediments unconformably overlying the earlier rocks; (4) the Q~aternary alluvium of Baker Valley and terrace gravel along 

the larger streams. 

The Permian volcanic rocks are characterized 

throughout by the dominance of albite, although 

residual andesine and labradorite are ·not unknown. 

They are highly altered and sheared, and the dark 

minerals have been largely altered to chlorite and epidote. The rocks recognized include keratophyre, 

quartz keratophyre, spilite, albite diabase, metaandesite, and metabasalt. They constitute a spyitic 

association in the sense of Dewey and Flett.3 Pillow 

structure, a common but riot invariable feature of spilitic lavas, was not recognized, although if originally 

present it may have been destroyed by later shearing. 

The formation is very thick, probably not less''than 

4,000 feet. It has been strongly, possibly isoclinally 

folded and strikes west-northwest in consonance,;J\Iith 

the regional trend of the pre-Tertiary formations of 

the Blue Mountains. 

Gabbro, diorite, quartz diorite, and albite granite 

intrude these Permian volcanic rocks. The diorites 

a Dewey, Henry, and Flett,. J. S., British pillow lavas and the rocks associated 

with them: Oeol. Mag., dec. 5, vol. 8, pp. 202-'209, 241-248. 1911. 

65 
66 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1932-33 

and gabbros are found widely in both the Baker and 

Pine quadrangles; the larger bodies of albite granite, 

however, though closely associated with these diorites 

...J 

<{ 

1-

<.J 

0 

~ 

0 

:;: 

Q. 

; 

1... 

0 

.;;:-

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en 

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oc 

..; 

co 

0:: "' cJi cJi 

1-' "' 1-' " 

w 

<t 

"" a: 

uJ 

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a: 

w 

~ 

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<ll 

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:§ 

and gabbros within the belt where they occur, seem to' 

be limited to a belt extending from a point near 

Hutchinson, in the Baker quadrangle, to the mouth 

of Maiden Gulch, in the Pine quadrangle. It is. 

perhaps significant that this belt of albitic granites. 

corresponds with the belt of Permian volcanic 

rocks, although the fact that a few smaller bodies 

of albite granite are found farther south, in the, 

midst of large gabbro masses in Carboniferous. 

argillite, seems to invalidate any suggestion of genetic relationship. The unconformably overlapping Tertiary and Quaternary formations cover 

much of the surrounding country, so that the. 

actual extent of the albite granites may be con-

~ siderably greater than is expos3d. These relations. 

~ are all brought out on Figure 1. 

-~ The age of the intrusive rocks is not known 

~ with certainty beyond the fact that they are post--

~ Permian and pre-Miocene. Lindgren/ on the·. 0 

:g basis of regional reconnaissance, tentatively re-- .o 

~ ferred them to a post-Jurassic, pre-Chico Ore-

~ taceous age. Differences in degree of meta-

§ morphism between the Permian and Triassic ~ 

~ rocks of the general region and the occurrence of 

~ fragments of a quartz diorite in Triassic breccia. 

"' & on Eagle Creek 5 suggest, however, that they £ may be in part of pre-Triassic age, as was sug--

'0 gested by Lindgren 6 for the gabbros and diorites. § 

~ of the Virtue district. Possibly the common 

~ association in other regions of albite granites 

~ and spilites pointed out by Dewey and Flett 1 

o may be considered as strengthening the prob--

~ abilities of a pre-Triassic age, as it may imply a. 

0 ~ consanguinity between the Permian volcanic. 

~ series and the later · albite granite; however,. 

~ this correlation is not supported by observaoa tions made in this area, except by the sugge~tive ~ ! geographic association of the spilites and albite: 

.s granite, and if the proposed hypothesis is sound 

~ ~ the origin of the albite granite has no con-

.;] nection with the extrusion of the greenstones, ~ 

s although it has a possible connection with their 

~ albitization. Indeed, it is possible that both 

ro pre-Triassic and post-Triassic gabbros and dio-

~ rites occur in the Blue Mountains, perhaps within_ l'il 

~ the area here considered. 

~ " The plutonic rocks of the region can be divided 

into at l-east two groups on the basis of the. 

metamorphism they have undergone. The older 

group, whose rocks in nearly 'every outcrop show 

signs of crushing and intense - deformation, 

embraces a wide variety of rocks ranging from 

pyro:xenite and gabbro through hornblende diorite, quartz diorite, and soda-rich quartz diorite . 

• Lindgren, Waldemar, op. cit., p. 596. 

s Idem, p. 734. 

6 Idem, p. 596. 

1 Dewey, Henry, and Flett, J. S., op. cit., p. 209. 
REPLACEMENT ORIGIN . OF ALBITE GRANITE NEAR SPARTA, OREG. 

(trondhjemite) to albite granite. The younger group 

-consists of biotite-qu~rtz diorite, subordinate . granodiorite, and a few related dikes and is ~ssentially 

undeformed in all its facies. This younger group, so 

far as now known, is not associ~ted with any occurrence of albite granite and win not be further discussed. 

Although albite granite occurs in gabbro in the 

southern part of the Baker quadrangle (not shown in 

fig. 1) it is ~ssociated with hornblende-quartz diorite 

where studied in detail,. near Magpie Peak> . on Goose 

Creek, and in Maiden Gulch. 

DIORITE AND QUARTZ DIORITE 

DISTRIBUTION 

Intrusive masses of the older group of gabbro, diorite, 

an<;l quartz diorite are abundant in the Blue Moun ... 

tains, from Prairie City to the Snake River, · a distance 

of about 80 miles. Considera.ble masses occur around 

M~gpie Peak, near Virtue Flat, and along Goose 

Creek and Maiden Gulch; smaller bodies occur on 

::Balm Creek, near Clover Creek, and near Haines. 

In places the dioritic rocks grade marginally into 

hornblendite and gabbro, elsewhere by increase of 

quartz to quartz diorite, or locally even to trondhjemite. 

'These changes are due to local variations in the quantitative relations of the common minerals and undoubtedly arose during the magmatic stage in the 

formation of the rocks. Transitfon to albite granite is 

of a different category, involving, it appears, processes 

that are not strictly magmatic in charncter. (See 

;J>P· 71-76.) 

II LITHOLOGY ''-' 

- In hand specimens the common diorite is a mediumgray equigranular rock, with average grain about 2 to 

4 millimeters in diameter. Plagioclase and hornblende are conspicuous. Quartz is visible in some 

:specimens but absent from others. 

.Under the microscope the rock shows a typical 

gr.anitic texture. Euhedral and subhedral plagioclase 

.and hornblende occur, sepa,rated by interstitial quartz. 

·Orthoclase is present very spa.ringly, making up hardly 

.3 per cent of the rock. A few grains of augite, now 

largely altered to &ctinolite, QQcur, with accessory 

titanite, apatite, magnetite, and ilmenite. 

The plagioclase · (andesine) is zoned normally, with 

'COres of composition near AblioAnt~o a.nd border zones 

about AbaoAn,o. In most thin sections it is slightly 

saussuritized, with minute epidote grains and locally 

a little sericite, set in an albitic base, but many quite 

unaltered grains occur. Ordinarily as in most other 

examples of saussuritic alteration, there has been but 

little rnigra.tion of material,. the bulk cmnposition of 

the original feldspar being essentially duplicated by 

that of the mineral aggregate replacing it. 

Orthoclase is a minor constituent occurring interstitially to all the other minerals. Quartz is present in 

varying amounts, commonly only a few per cent, and 

shows norma.l granitic relations, as it is interstitial to 

the plagioclase and mafic minerals. "':..: ·.:f · 

Most of the amphibole is common green hornblende. 

It is pleochroic in yellowish green ~nd greenish brown, 

X <Y = Z. It is optically negative, with moderate 2V, 

an extinction angle of 22° Z/\c, birefringence ahout . 

0.021. Some alteration to . chlorite has occiDTed in a 

few specimens. 

Small amounts of epidote in addition to that in ,the 

saussurite also occur in veinlets penetra.ting the :rock. 

Aside from their marked association with ,the lll4tfic 

minerals, nothing noteworthy was observed respecting ' 

the accessory minerals. 

ALBITE GRANITE 

DISTRIBUTION . I 

' The largest mass of albite granite in the area is that 

near Spartfi:, where it was first recorded by Lindgren. 8 1 

A detailed survey of this mass has not been carried out, , 

and the outlines given in Figure 1 are taken from · an ! 

unpublished reconnaissance map by. C. P. Ross. It is t 

known to contain considerable areas of nonalbitic· rock, I 

although the most conspicuous exposures consist of 1 

albite granite, doubtless because of the high ·quartz f 

content and consequent resistance to erosion of this 1 

rock. Another large body crops out in the canyon of , 

Goose Creek. Sn1aller bodies occur (1) near the mouth · 

of Maiden Gulch, (2) just east of Clover Creek in see. 

1, T. 8 S., R; 42 E., (3) around Magpie Peak, (4) near 1 

the corner of Ts. 6 and 7 S., Rs. 39 and 40 E., and (5) 

northeast of Hutchinson. 

All the larger bodies are very closely associated with 

masses of diorite or quartz diorite. Detailed examina"' 

tion of the favorably exposed masses, particularly t4at 

along Goose Creek and that at the mouth of Maid,en 

Gulch, reveals gradational phenomena. These·; with ' 

the transitional varieties of rock, can be more appro ... I 

priately discussed after representative specimens of 

the albite granite have been described. 

LITHOLOGY 

MEGASCOPIC FEATURES I 

Over considerable areas the albite gr&nite is sheared : 

and even IJlyloniti~ed. The more intensely sheared l 

parts are r~duced to streaked rocks,. with epidote and. 

quartz veinlets penetrating a chalky-appe~;tring but ' 

firm, flinty groundm&ss in which fe~dspar but no dark 1 

minerals can be seen, Elsewhere the rock shows les& 1 

conspicuous shearing, although it seems everywhere to 

be somewhat rn~re brecciated than the adjoining l 

diorite or q_uartz diorite. 

There is a marked inverse correlation between tha 

amount of shearing· that a specimen of this gr3,llite has 

undergone imd the amount of Inafic material it contains. Thet more sheared the rock the less recognizable , 

amphibole it retains and the more greenish S.,re . the , 

feldspars from mcluded epidote. 

s Lindgren, Waldemar, op. cit., p. 734. 

'. 
68 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1932-33 

The less crushed albite granite is a medium-gray, 

almost equigranular rock in which plagioclase, amphibole, and quartz of a notably blue hue are recognizable. 

The grain size averages about 2 to 4 millimeters. In 

the more sheared portions the dark minerals are less 

plentiful and the quartz more prominent. Some of 

these rocks show a remarkable pseudoporphyritic 

texture, with large irregular aggregates of bluish quartz 

as much as 2 centimeters in diarneter set in a groundmass of greenish plagioclase and subordinate epidote. 

In son1e specin1ens there are small veinlike masses of 

bluish quartz 3 or 4 centin1eters long and 2 to 5 millimeters wide. 

MICROSCOPIC FEATURES 

TEXTURE 

In thin section the albite granite is extren1ely variable 

in both texture and mineralogy. Textural varieties 

include granitic, micrographic, myrmekitic, cataclastic, and crystalloblastic, but gradations between 

nearly all these va.rieties are to be found. 

Granitic texture.-Some slides superficially resemble 

those· of the quartz diorite in a striking manner. The 

feldspar grains are of about the same size, from 2 to 4 

millimeters in diameter; the hornblende does not 

noticeably differ from that of the quartz diorite. 

Quartz is, however, noticeably more plentiful, and its 

habit is considerably different from that of the quartz 

diorite in that it is not confined to wedge-shaped 

interstices between the feldspar grains but occurs also 

in irregularly l bate and vermiform masses partly 

embedded in the plagioclase. (See pls. 19, A; 22, C. 

D; 23,.A.) 

Micrographic texture.-Locally the albite granite has 

a handsome micrographic texture (pl. 19, B) and elsewhere a less regular graphic texture (pl. 23, 0). The 

grain size is, of course, much less uniform than in the 

varieties with normal granitic texture. Rosettes of 

graphically intergrown albite and quartz attain diameters of 3 millnneters or even more. These specimens 

are characteristically less mafic than the granitic 

varieties. 

Myrmekitic texture.-The albite granites are notably 

more rnyrmekitic than the quartz diorite. Typical 

"brairi.-coral" myrmekite is common (see pl. 19, 0) 

but always in small amounts. There seems to be a 

gradation between myrmekitic and graphic texture, 

and the association is so close and so striking as to 

impel the belief that they are of common origin. Much 

myrm,.ekitic intergrowth is found where no potash feldspar is to be seen. Myrmekite is also present, though 

not abundant, in the cataclastic albite granite. 

Cataclastic texture.-Many of the more siliceous albite granites are notably cataclastic, all. gradations 

from mere mortar structure to complete n1ylonitic 

schistosity being seen. (See pls. 19, D; 20, A.) There 

is a marked direct correlation between the presence of 

brecciation and high quartz content. 

Orystalloblastic texture.-A very few specimens of albite granite have typical crystalloblastic textures. 

These are very poor in dark minerals: (See pl. 20, B.) 

MINERALOGY AND MINERAL HABITS 

The minerals of the albite granite include plagioclase, quartz, amphibole, biotite, titanite, "iron ores," 

zircon, apatite, rutile (?), epidote, clinozoisite, sericite, 

and chlorite~ 

Plagioclase.-The plagioclase · commonly resembles 

superficially that of the diorite, both in dimensions 

and in inclusion-marked zones. It is, however, not 

andesine but albite, glassy and clear around the borders of the grains in zones commonly about one-fifth 

of the thickness of the grains. The inner parts of 

many of the plagioclase crystals are obscured by masses 

of highly refracting grains of epidote, clinozoisite, .and 

sericite. These n1asses so thoroughly mask the feldspar base in which they are embedded that its composition is not certain, although it seems to be albite 

of the same index as that in the clear zone about it. 

(See pls. 20, 0, D; 23, B.) This variety of albite is 

closely analogous to the products of normal saussuritization. However, there is considerable evidence, outlined later, that its formation was part of a more 

fun dam en tal change. 

A few specimens contain water-clear albite with no 

saussuritic products. This clear variety is commonly 

found in the rock having crystalloblastic texture and 

less commonly in the other rocks. · 

In a very few specimens two varieties of plagioclase 

are found-a central core of andesine surrounded by 

a wide rim of partly clear, partly cloudy albite. 

Tongues and vermicular and scalloped masses of albite 

anastomose through the central core of andesine in a 

very complex manner. The significance of this relation 

is referred to below. Certainly the irregular boundaries between the albite and andesine are not normal 

zoning. (See pl. 23, D.) 

In the graphic varieties the albite is cloudy but 

contains no recognizable epidote or· sericite inclusions 

and forms rosettes radiating from a central crystal, 

which commonly has both polysynthetic and carlsbad 

twinning. The central crystal, as well as the radiating · 

rosettes, commonly includes blebs, and dotlike and 

hooklike masses of quartz, all of which show uniforn1 

optical orientation over considerable segments of a 

single rosette, though two to five or more such quartz 

crystals are required to compose the entire rosette. 

(See pl. 21, A, B, 0, D.) 

Myrmekitic albite possesses the usual features of 

the texture. (See pls. 19, 0; 2i, D.) 

A good many specimens show the variety known as 

chessboard albite. (See pl. 22, A . .) This is characterized by polysynthetic twinning which does not pass 

entirely across the crystal but is interrupted at cross 

lines by oppositely oriented twins, resulting in a steplike extinction reminiscent of a chessboard. (Seep. 73.) 
U. S. GEOLOGICAL SURVEY 

A. ALBITE CRYSTAL (a) EMBAYED BY QUARTZ (q) IN 

STRUCTURE INTERPRETED AS DUE TO REPLACEMENT . 

C. "BRAIN-CORAL" MYRMEKITE IN ALBITE GRANITE 

Dark areas albite; light areas quartz, 

PROFESSIONAL PAPER 175 PLATE 19 

B. MICROGRAPHIC TEXTURE OF ALBITE GRANITE 

a, Albite; q , quartz. 

D. CATACLASTIC ALBITE GRANITE 
U. S. GEOLOGICAL SURVEY 

A. CATACLASTIC ALBITE GRANITE 

a, Albite; q, quartz. 

C. ALBITE GRANITE 

Showing saussuritic plagioclase (s) with ·rim of clear albite (a) sur- rounding it; some sericite in the core. q, Quartz. 

PROFESSIONAL PAPER 175 PLATE 20 

B. CRYSTALLOBLASTIC ALBITE GRANITE 

a, Albite; q, quartz. 

D . ALBITE GRANITE 

Broken plagioclase with saussuritic center (s) and clear albite border (a) partly replaced hy blebs and tongues of quartz (q). In upper part a clear albite rim is in marked contrast with its saussuritic core, 
U. S. GEOLOGICAL SURVEY 

A. ALBITE (a) SURROUNDED BY MICROGRAPHIC ROSETTE OF ALBITE AND QUARTZ (q) 

C. ENLARGED OUTER FRINGE OF MICROGRAPHIC INTERGROWTH SHOWN IN A 

a, Albite; q, quartz. 

PROFESSIONAL PAPER 175 PLATE 21 

B. ENLARGED PHOTOGRAPH OF BORDER OF MICROGRAPHIC INTERGROWTH AGAINST THE CENTRAL 

ALBITE CRYSTAL SHOWN IN A 

a, Alhite; q, quartz. 

D. GRAPHIC INTERGROWTH OF ALBITE AND QUARTZ 

SHOWING SOME RESEMBLANCE TO MYRMEKITE 
U. S. GEOLOGICAL SURVEY 

A. ALBITE SUO\VING TENDENCY TmVARD CHESSBOARD 

STRUCTURE 

C. WISPS OF HESIDUAL ALBITE (a) IN QUAHTZ WlllCll IS 

REPLACING IT 

All the albite shown extinguishes simultaneously. 

PROFESSIONAL PAPER 175 PLATE 22 

B. ALBITE GRANITE CUT BY VEIN LETS OF CLEAR ALBITE 

av, Albite vein; a, albite; q, quartz. 

D. ALBITE CRYSTAL (a) PARTLY REPLACED BY QUARTZ 

(q) IN PSEUDOGRAPHIC STRUCTURE 

Compare with Plate 21, A . 
U. S. GEOLOGICAL SURVEY 

A. ALBITE (a) BEING REPLACED BY QUARTZ (q) 

Note the common orientation of albite wisps near the large central 

crystal. 

C. ALBITE (a) PARTLY REPLACED BY QUARTZ (q) IN 

CRUDE GRAPHIC STRUCTURE 

PROFESSIONAL PAPER 175 PLATE 23 

B. SERICITIC ALBITE (sa) COATED AND VEINED BY CLEAR 

ALBITE (a, av) 

D. CENTRAL CORE OF SOMEWHAT SAUSSURITIC ANDESINE (an) SURROUNDED BY ALBITE (a) IN RELATION 

INTERPRETED TO SIGNIFY REPLACEMENT 
·"' 

REPLACEMENT ORIGIN OF ALBITE GRANITE 'NEAR SPARTA,· OREG. 

-· A rlittle S:}oite o~curs in nanrow veins filling cracks 

__ in ,ther0cksJ- (See I_l>L 22, B.) Such veins pass through 

--.,._ ___ quartz, cloudy albite, and mafic minerals indifferently. 

(Seep. 73.) 

The albite of these rocks has extinction angles as 

great as 16° in the zone normal to 010, and of 18° 

between a' and Q01 · in sections normal to 'Y· . Some of 

it i~ therefore at le·ast as sodi¢1 as Ab96An4 , and much 

of it is probably even more sodic.. In many specimens 

the ~dices of refraction are ~Jl lower than 1.54, although in a few the composition is probably as calcic 

S:s A b9zAn8• 

1 Quartz.'.,_ The quartz of these rocks has diverse 

habits. Some is simply interstitia] to the feldspars, 

as m the.· quartz diorit<B, but most of it has lobed edges 

~gainst the feldsp~r (see pls. 19, A; 22, 0; 23, A), and 

p_!esents convex contacts toward it in very involved 

patterns extending through the feldspar. Some occurs 

in ·patches isolated within ' feldspar grains; some obviously veins and cuts all opher minerals. Many of 

the crystals are brecciated,' all gradations being seen· 

from 'so-called "strain shadows" to quartz flour in 

some of the severely rriylonitized specimens. 

The quartz is notably bluish and is similar to ·the 

bluish)augen quartz of m.any schists. The oil-imnlersion lens reveals many minute, very elongate needles 

in the quartz, and the color is doubtless due to these 

needles. Their identity cou]d not be proved, but they 

rese.mble rutile. 

Arp,pkibole.-Two varieties of amphibole occm.r. 

One is apparently common hornblende, like that of 

the quartz diorite. It has the following optical proper-

~ies: Extinc.tion angle 21° "f/\C, birefringence about · 

0.025, optically negative, 2V moderate, Z bluish 

green, Y brownish green, and X yellowish green 

. ~>Y>X. These properties do not indicate any 

notable content of alkalies. However, in some specimens the common green hornblende is blotched, espe-

~ially toward the ends of individual crystals, wrth 

greenish-blue patches ,having different .optical properties. In several specimens the principal amphib~le 

has the properties of the bluish parts of these blotchbd 

hornblendes, as follows: Extinction· angle 28°-:y/\c, 

~il'efn·nge:rl.Ce .low~ surely , les~ th .. an ?.015 (the stro~i g 

colors rendering Its measurement difficult), optica ly 

negati;re, 2V very small, pleochroism Z = Y a del.p 

gr~enish blue> X, light yellow-brown. These prop : rt~es agree with those of hastingsite. 

Biot,ite.-Many specimens carry small amounts of 

biotite of the common variety, mostly as an alteration 

P,ro?uct of hornblende, although some seems ,to be of 

iridependent origin. It is nowhere the dominant mafic 

:r:niD:eral, although much more plentiful than in the 

quar~z . diorite. 

Sericite.-Considerable sericite occurs in the saussurit~ed variety of plagiochise. J ,., • 

. 8pidote.-The dominant dark mineral in most 

specimens is epidote. It occurs with. clinozoisite . in 

the salll.ssuritized plagioclase, and locallyr ;irt1 hows 1 ' 

very m<Rrked tendency to develop: in tlile centJrfiihcoJFeS 

of the , plagioclase. It also occu:rs as· an .alterati0nr 

product of hornblende and as . independ-ent ·· v~Jn ~ 

through the rock. , ' ' u.t~ 1 1 

Subordinate minerals.-As a rule, access<i>:uy :m.inero:lS> 

are far less plen.tiful in the albite. granite .than ,ip tmeJ 

quartz , diorite.. Anwng them, titanite is · 1 JRestl 

abnn;el~nt, iron ores next, and apatite, zircon.,1.-alitd 

rutile (?) follow in order of deereasing quantit.y. ... 

Chlorite is common in small quantities . as an a1teF~~ 

tion product of the mafic minerals , ·especially· ini.ass@'-

ciationJwith iron ore, after hornblende. I •: I I 

ZONE GRADATIONAL BETWEEN QUARTZ DIOR,ll'E 4N:g 

ALBITE GRANITE 

FIELD RELATIONS ·, I! 

At two localities-on the hillsid~ nprth of the ;M~cy 

mine, near the mouth of Maiden : Gulch, and the hills. 

on botp sides of Goose Creek, in sees. 4, 8, 9,. anp 'to,' 

T. 8 S., R. 43 E.-it is possible to examine in d'etaif , \ I d l 

the mutual relations of the quartz diorite and a~ bi~el 

granite. At both these localities the.,rocks a;re p~11;1-1 nected by intermediate varieties so that the cont~ct .. !s •I '•· ' 1( • 1 

gradational. . 1 I I \ I - • ~ 1 

Near the Macy m~ne, in Maiden Gulch, where the 

exposures are somewhat nwre nearly complete than at 

Goose Creek, a zone about 1,00()-,feet wide shows a 

passage 'from dark-gray, almost quartz-free 'diorite to 

light-gray, highly quartzose albite · granite. The tra-Ii-; 

·sition is igradual, being marked first by :increasing ·qna:ti-· 

tities of quartz, appearing along breccia surfaces, then 

by increasing quantities of biotite relative to hortil·' 

blende (although. the total quantity of mafic minerals 

is declining), then by the appearance of bluish ql:tartz· 

grains .in. the mass · of the rock, and finally · by· the 

marked diminution of dark minerals and a corre'spond.:. 

jng inqrease of light minerals throughout the rock. 

At the Maiden Gulch locality the extreme variety of 

albite granite, such as is widely developed near Goose 

Creek and especially near the Gem mine at Sparta, is 

not found. This variety is pseudo porphyritic and cqntains great quantities of quartz in blebs as much 3Js, 2 

centimeters in diameter and numerous connecting v~;n~1 

lets, in a matrix aonsisting of rather coarse green~h 

plagioclase and almost negligible quantities of biotite) 

and amphibole. ' , 

Gradations between the Maiden Gulch variety ~ri:q. ; 

the pseudoporphyritic variety are to be found boilr 

near Sparta and near Goose Creek. The Goose Cre,~k; 

transition zone is less con1pletely exposed than that'~, <Jf , 

lv,faiden Gulch, but identical transition features are ti 

be found there. 

LITHOLOGY 

The microscope confirms the conclusion drawndrom 

field studies, that the quartz diorite is gradatiolilal; t'o 

the albite granite. Microscopic features of typical 
70 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1932-33 

quartz diorite and albite granite have been described. 

The features recognized under the microscope in specimens from the contact zone include, in passing from the 

diorite to the granite, .(1) an increase in the quantity of 

quartz, which locally reaches extremes of fully 50 pet 

cent, and a change from an interstitial habit to lobate 

and penetrative forms toward the feldspar; (2) a 

change in the plagioclase, in some specimens merely to 

saussurite, in others by the development of clear albite 

·rims about saussurite cores, in still others by the devel~ 

opment of tonguelike protuberances of albite in but 

slightly altered andesine; (3) a change in the hornblende by partial alteration to biotite and by the 

spotty development of hastingsite both internally and 

at the ends of crystals; (4) a marked decrease in the 

total quantity of mafic minerals; (5) a change in the 

accessory minerals by marked decrease of all except 

rutile (?),which makes its appearance in quartz. 

Concomitant with these mrneralogic changes are 

textural changes in the direction of decrease in simplJ 

granitic texture (hypidiomorphic granular) and marked 

increase in cataclastic, myrmekitic, and micrographic 

textures. Crystalloblastic texture is rare and is apparently confined to the albite granite, as it is no~ 

present in any transition rocks examined. This limitation may be of genetic significance. 

CHEMICAL FEATURES 

The field relations of the albite granite and quartz 

diorite taken together with . the microscopic features 

just ~ummarized have led to the conviction that the 

two rocks are most intimately related and are connected · 

by a complete transition series. To test this question 

further, chemical analyses were made of representative 

specimens of the quartz diorite and albite granite and 

of two intermediate rocks. These analyses seem to 

show that there is an almost cQmplete gradation 

between the two end members. 

Analyses of quartz diorite, albite granite, and transitiooal phases · [J. G. Fairchild, analyst] 

Si02---------- - -------- Al20a- ________________ _ Fe20a- __ --- _- _- _· __ ___ _ FeO _________________ _ 1dg0 __________ ____ __ _ 

CaO _______ _____ _____ _ 

~a20-------~------

K20- - - - -- - -- - - -- -- - - - H20- ------- - - - -- -- -- - H20 + ~ _--------------- Ti02--------------- --- C02 _____ ________ _____ _ 

P20s~--------- ------- Mn0_ .. _______________ _ Bao _________________ _ SrO _·.: ___ _____________ _ 

54.67 

15. 95 

2. 08 

7. 48 

4. 09 

7. 97 

2. 71 

1. 16 

0 

1. 26 

1. 16 

1. 24 

.11 

. 17 

0 

0 

2 

67. 81 

14. 13 

1. 50 

4. 04 

1. 56 

3. 76 

3. 36 

1. 62 

. 06 

1. 24 

. 79 

. 45 

. 06 

. 13 

0 

0 

73. 81 

12. 36 

. 94 

2. 97 

:78 

1. 62 

3. 89 

1. 47 

. 04 

. 90 

. 70 

. 31 

. 04 

'10 

0 

0 

100. 05 100. 51 99. 93 

1. Quartz diorite, sec. 9, T. 8 8., R: 43 E. 

2. Partly albitized quartz diorite1 same locality. 3, Pseudo porphyritic albite gramte, sec. 8, T. 8 8., R. 43 E. 

4.':Pseudoporphyritic albite granite, sec. 13, T. 8 8., R. 43 E. 

4 

77.04 

11. 88 

1. 05 

1. 32 

. 04 

1. 28 

4. 45 

1. 64r 

0 

. 54 

. 37 

. 14r 

. 04 0 . 

0 

0 

99. 79 

The norms, computed in accordance with the classification of Cross, Iddings, Pirsson, and Washington, 

are as follows: 

1 2 3 4 

Quartz _______ 10. 50 30. 04 40. 48 42. 12 

Orthoclase ____ 7. 23 9. 45 8. 90 9. 45 

Albite ________ 23. 06 28. 30 33. 01 37. 73 

Anorthite _____ 27. 80 17. 79 7. 23 5. 56 

Corundum ____ ------------- . 31 1. 73 . 82 

Diopside ______ 3. 00 ------------- - ------- --- - ·-- Hypersthene __ 19. 14 8.~4 5. 46 1. 19 

Magnetite ____ 3. 02 2. 09 1. 39 1. 62 

Ilmenite ______ 2. 28 1. 52 1. 37 . 76 

Apatite _______ . 34 . 34 . 34 . 34 

Not used ___ __ 2. 50 1. 30 . 94 . 54 

98.87 100. 06 100. 85 100.13 

SymboL ______ Il.4 ( 5) .{3) 4.4 (I) II. (3)4.3.4 1".3.2.4 !.3."2.4 

These analyses have been recomputed into modal 

minerals on the basis of the microscopic study of the 

rocks. The textures of the rocks are not favorable to 

accurate measurements by the Rosiwal method, but 

the computed mineral composition agrees fairly well 

with the estimated proportions observed. 

Approximate mineral composition of quartz diorite, albite granite, 

and transition rock 

1 2 3 4 

Quartz ________ 12 33 42 41 

Albite ____ __ __ _ 23. 5}40 ~}34 e~}29 e8. 5}40 Anorthite ____ __ 16. 5 1.5 

Orthoclase a __ _ _ 7 5 4 5. 5 

Hornblende ____ 26 11.5 8 .5 

Hastingsite ____ ---------- .5 1.5 .5 

Epidote _______ 3 2. 5 4. 5 4. 5 

Biotite ________ 1 5 ---------- 1 

Sericite ________ --------- - 2 5 5 

Titanite _______ 2 1 1 . 5 

Ilmenite _______ 1 1 1 .3 

Magnetite _____ 2 2 . 5 .5 

Chlorite ____ ___ 2. 5 1 2. 5 .7 

Calcite_ .. ______ . 3 1 .7 .3 

Apatite ________ . 5 .5 . 1 . 1 

100.0 100. 0 

I 

99.8 100. 4 

.a Most of the potash feldspar is occult, probably in solution in the plagioclase. 

CONCLUSIONS RESPECTING RELATIONSHIP 

All the lines of evidence cited-field, microscopic, 

and chemical-are believed to point to a complete 

gradation between the diorite and the albite granite. 

The transition frmn one rock to the other can be 

traced in the field relations, in the mineralogy, in the 

texture, and in the chemical composition. Moreover, 

the continuity of the transition implies that the differences between the two facies arose in place and did 

not result direetly from differentiation at depth. The 

direct relation between the intensity of the crushing 

of a rock and the increase in the quantity of the minerals characteristic of the albite granite (quartz, albite, 

and hastingsite) which it possesses is further evidence 

in favor of a derivation of the albitic rock in place, for 

. . 
REP~ACE~ENT 71 ORIGIN OF. ALBITE , RANITE ~EAR S~ARTA, O~EG. . . • 

it suggests that the modificatiOns took place ill the structures ill basaltic lavas, Involvillg calcic plagioclase 

rock after it became solid. Moreover, it suggests cdres and albite rims, have been attributed to albitstrongly that the albite granite is an albitized and izktion replacement by Bailey and Grabham. 12 Gillsilicified facies of the quartz diorite and that the sdn 13 has noted in two localities labradorite cores 

albitization was localized by zones of brecciation along rrounded by irregular andesine borders and penetrawhich silica and soda-bearing solutions gained ready tipns which he interpreted as evidence of replacement. 

access to large volumes of rock. According to this s~· ar observations have been made by ·Kinoshita. 14 

suggestion, the albite granite is the product of n1eta- ! e relations exhibited in t~e Sparta roc~s are ~h~wn 

_morphic replacement localized through mechanical I Plate 23, D. Holmquist has described similar 

-openings that were due to orogenic processes. rdplacements of calcic feldspars by sodic ones, interSeveral features in the rocks·point toward such an pfeting them as reaction products of inclusions.15 

·origin of the albite granite, and none that are known Myrmekite is recognized as a replacement product. 

to the writer are out of harmony with such an origin. ~both metamorphosed and ~et.amorphosed rocks. 16 

·The evidence afforded by the texture and . mineralogy T~onquoy 17 has suggested that It IS the result of a spe-

-of the rocks, so far as their bearing upon the genesis dal mode of albitization, which he refers to "autopneuwas recognized, is discussed in the following sections. rrtatolysis," after consolidation of the rock. He points 

Oflt that myrmekite, though favoring the contacts 

brtween plagioclase ·and microcline, is not limited to 

srh contacts, but may occur, contrary to the dictum 

o Becke,18 on the contact between two microcline 

c stals or even on the contact with quartz. 19 He accfrdingly suggests that it is localized by accidental 

openings through -which the albitizing solutions gain 

access to the microcline crystals. Mechanical as well 

a~ chemical factors thus play parts in localizing the 

clyrmekite, and it is for this reason, in the opinion of 

'lironquoy that slightly cataclastic rocks, as has long 

b~en reco · ed, furnish especially favorable environclents for myrmekite. Inasmuch as the special form 

of albitiza ion represented by myrmekite occurs in conj~ction ith the chemical and mineralogical transit~ons pre ·ously described, the existence of at least 

sbme alb tizing solutions in the albite granite is 

drmonstr ted. A local source of the soda and silica 

in myrme · te formation has been generally accepted, 

pbssibly · th some justification, but Sederholm 20 

admits an Tronquoy 21 demands the presence of circulJting al alic sotutions of extraneous source in its 

rmation In the present occurrence the marked 

a~sociatio of the myrmekite with the cataclastic 

a bite gra ite, with soda-bearing amphibole, and with 

EVIDENCE OF LATE MAGMATIC OR HYDROTHERMAL 

MINERAL FORMATION 

TEXTURAL EVIDENCE 

The cataclastic features of the albite granite could 

have been developed only after nearly complete consolidation of the rock. The cataclastic rock shows in 

some places nonsaussuritic, in many places only slightly 

saussuritic, albite crystals of sizes and shapes and 

having zonal arrangements of inclusions which are 

nearly identical with those of the andesine crystals 

<>f the quartz diorite. That these crystals are pseudomorphs after the andesiqe of the diorite is highly 

probable. This strongly suggests postmagmatic albitization, although the observation in itself does not 

prove that the albitization accompanies the brecciation. These feldspars differ from the saussurite 

pseudomorphs occurring in some of the rocks transitional to the quartz diorites, although even these 

·saussuritic feldspars are probably due to hydrous 

solutions, 9 inasmuch as zoisite is a hydrous silicate, 

and they suggest, if they do not demand, dynamic 

processes for their formation. 1° Chemical evidence 

proves, however, that even the saussuritic feldspar of 

the albite granite differs notably in bulk composition 

from that of the quartz diorite. (See norms on p. 70.) 

Some of these transition rocks yield other specimens 

in which only slightly altered andesine is inclosed by 

dear albite, with irregular contacts involving marked 

embayment f andesine core by the surrounding 

albite. These specimens strongly suggest attack by 

sodic solutions on the earlier andesine and its partial 

replacement by albite, for the relation is not mere 

zoning and the phase relations of the plagioclase 

system prohibit the coexistence in contact of albite 

&nd andesine in equilibrium.U The albite pseudomorphs after andesine are believed to represent the 

end stage of this replacement process. Similar 

9 Grubenmann, U., and Niggli, P., Die Gesteinsmetamorphose, I, p. 317, Berlin, 

1924. 

to Smirnoff, N., Recherches sur !'albitisation des roches eruptives: Arch. sci. 

phys. nat., vo). 37, pp. 512.:..528, Geneve, 1914. 

11 Bowen, N. L., The evolution of the igneous rocks, p. 34, Princeton, 1928. 

!2 Bailey, E. ., and Grabham, G. W., Albitization of basic plagioclase feldspars: 

Geol. Mag., de . 5, vol. 6, pp. 2~256, 1909. 

a Gillson, J. ., Petrography of the Pioche district, Nevada: U. S. Geol. Survey 

Pt of. Paper 1 , p. 80, 1929. Gillson, J. L., and Kania, J. E. A., Genesis of the 

eritery deposits near Peekskill, N. Y.: Econ. Geology, vol. 25, pp. 514-515, 1930. 

1• Kinoshita, K., On the'' Kuroko" (black ore) deposits: Japanese Jour. Geology 

and Geograpli , vol. 8, p. 295, 1931. 

1s Holmquist P. J., Studien iiber die Granite von Schweden: Geol; Inst. Upsala 

B1Jll., vol. 7, p . 157, 165, pl. 17, fig. 9, 1906. 

16 Sederholm, J. J., On synantetic minerals and related phenomena: Comm. geol. 

Finlande Bull. vol. 9, No. 48, p. 139, 1916. -

r7 Tronquoy, R., Origine de la myrmekite: Soc. francaise mineralogie Bull., vol. 

351 pp. 221-222. ~.912. . . . 

~s Becke, F., ber Myrmek1t: Mm. pet. M1tt., Band 27, p. 381, 1908. 

19 See also schirwinsky, Peter, Quantitative mineralogische und chemische 

z+sammensetz ng der Granite und Greisen, pp. 673-£74, Moscow, 1911, who likewise 

estions Bee 's dictum. Gerald Andrew (The contact relations of the DonegaJ 

granite, Irish F ee State: Manchester Lit. and Philos. Soc. Mem. and Proc., vol. 72, 

p.

1 215, 1928) d cribes myrmekite in plagioclase, which supports Tronquoy's idea 

th t the produ tion of myrmekite is a special form of albitization and is not dependeDit on local rna rial only. 

lo Sederholm, J. J., On migmatites and associated pre-Cambrian rocks of southw~stern Finlan : Com~. geol. Finlande Bull., vol. 12, No. 77, p. 131, 1926. r Tronquoy, R., op. Cit., p. 221. 

I 

I 
'r. 

72 SHORTER CONTRIBUTIONS TO GENERAL GEObb6Y, .1932-33 

quartz that is dominantly lobate toward the plagioclase 

strongly suggests that it was formed by introduced 

solutions not derived from immediately contiguous 

parts of the mass. 

The micrographic texture that is so common in the 

albitic rocks is not clearly distinguishable in all phases 

from the myrmekitic texture. Similar difficulty in 

distinguishing them has been experienced by Tschirwinsky ?a and by Bergt.a3 Goldschmidt a4 has described 

a "pseudogranophyric" texture resulting from endstage replacement of potash feldspar by myrmekite. 

Gradations from normal graphic intergrowth into 

"quartz vermicule" (myrmekite) in the Bathgate and 

Linlithgow Hills, Scotland, are described by Falconer,25 

who regards some of the graphic intergrowth as doubtless replacing earlier feldspar. Although many other 

writers express confidence that the. two textures have 

nothing in common,26 and certainly no one can fail to 

recognize the differences between the typical developments of the two, the present writer can not escape the 

belief that the tendency to view them as readily distinguishable in all aspects and of entirely distinct 

conditions of origin is due in large part to the dominance of the view, first tentatively suggested by Teall, 

that graphic textures are the result of eutectic crystallization a

7 and hence can have nothing in common with 

the myrmekitic intergrowths, which are universally 

accepted as replacement phenomena. 

The view that graphic textures are conclusive evidence of eutectic intergrowth has many strong adherents even at the present time/8 although the idea 

has been severely criticized by Judd, 29 Mennell,30 

Collins,31 Warren and Palache,32 Bastin,33 Fenner,34 

22 Tschirwinsky, Peter, cited by Tronquoy, R., op. cit., p. 215. 

23 Bergt, W., quoted by Becke, F., op. cit., p. 380. 

24 Goldschmidt, V. M., Ubersicht der Eruptivgesteine im kaledonischen Gebirge 

zwischen Stavanger und Trondhjem: Vidensk. Ski'ifter, I, Mat.-Naturv. Klasse, 

1916, No.2, p. 78. 

2s Falconer, J. D., Igneous geology of the Bathgate and Linlithgow Hills: Roy. 

Soc. Edinburgh Trans., vol. 45, pp. 144-145, 1908. 

26 Sederholm, J. J., op. cit., p. 70. Becke, F ,~ op. cit., p. 380. Tronquoy, R., ·op . 

cit., pp. 217-219. ' · 

21 Teall, J. J. H., British petrography, p. 401, 1886. Vogt, J. H. L., Die SilikatschmelzlOsungen, 1: Vidensk. Skrifter, I, Mat.-Naturv. Klasse, 1903, No.8, p .103; 

On the terms eutectic, etc., and their importance in petrogenesis: Jour. Geology, vol. 

39, pp. 422-424, 1931. Brogger, W. C., Die Mineralien der Syenitpegmatitgange der 

siidnorwegischen Augit und Nephelinsyenite: Zeitschr. Kryst. Min., Band 16, 1890, 

p. 148. Harker, Alfred, Natural history of the igneous rocks, pp. 171, 271-272, 297, 

London, 1909. Iddings, J. P., I gneous rocks, 2d ed., vol. 1, p. 210, New York, 1920. 

Rosenbusch, Harry, Elemente der Gesteinslehre, 4th ed., by A. Osann, p. 302, 

Stuttgart, 1923. 

28 Vogt, J. H. L., The physical chemistry of tbe crystallization mld magmatic 

differentiation of igneous rock. Jour. Geology, vol. 29, p. 324, 1921. Tschirwinsky, 

Peter, op. cit., pp. 672-674; Anchi-stoichi<imetrische Typen der Biotitgranite nach 

ihrem theoretischen Feldspatgemische geordnet: Neues Jahrb., Beilage-Bd. 53A, 

pp. 209-228, 1926. . 

29 Judd, J. W., On the growth of crystals in igneous rocks after their consolidation: 

Geol. Soc. London Quart. Jour., pp. 17~186, 1889. 

3o Mennell, F. P., Basic dykes and rock genesis: Geol. · Mag., dec. 5, vol. 8, 

pp.14-15, 1911. 

s1 Collins, W. H ., Onaping map area: Canada Geol. Survey Mem. 95, pp. 5lHi2, 

1917. 

a2 Warren, C. H ., and Palache, Charles, The pegmatites of the riebeckite-aegirite 

granite of Quincy, Mass., U. S. A., their structure, minerals, and origin: Am. 

Acad. Arts ail,d Sci. Proc., vol. 47, p. 147, 1911. 

33 Bastin, E. S., Origin of the pegmatites of Maine: Jour. Geology, vol. 18, p. 312, 

1910. 

34 Fenner, C. N., The Katmai magmatic province: Jour. Geology, vol. 34, pp. 

750-754, 1926. 

and many other petrologists, A. replace;me~t .:arjgin, 

for some graphic intergrowt;hl$ ha& b,~e:n pr(j>ye p}f t~~p; 

presence in certain adm~Jes, 5 i a;nd ·, Scl ~ller/t~ f. · , 

given reason to. suspect a replacement origffic c;) r-t4~ 

structure in some pegmatites. The possibility of a 

replacement origin of the structure has also been 

suggested by Aurousseau 37 for granophyres. Many 

mineragraphers have in recent years q1,1estioned the 

eutectic origin of this structme in ore .. min,erals.3s 

Although Tyrell regards some graphic textY~es as of 

eutectic origin, he agrees that they can form: in,.Qther 

ways. 39 .,, 1 

Sugi 40 has recent]y given very sl}.ggestive evidence of 

a repla,cement origin for some micrographic intergrowths in certain Japanese injection rocks. , ~skow 41 

finds the texture in some albite gra.nite :rui~tites in 

Sweden. Wells and Wooldridge 42 have interpreted 

micropegmatite in a granophyre on the island of 

Jersey as in part of eutectic origin and in part due to 

late replacement by silica. Where the replaced feldspar is aJbite the resulting product is "myrmekite." 

Similarly, the writer regards some of the graphic 

intergrowths seen in the Sparta rocks, especially such as 

are illustrated in Plate 21,A, B, where theinterg:rowth 

is clearly perched on a weB-developed crystal face of 

albite, to be due to simultaneous crystallization of 

quartz and albite. Other areas of similar intergrowth,, 

however, even the inner zone of the same intergrowth,. 

as in Plate 21, B, appear to be clearly due to replacement-so that the structure is not in itself evidence of 

any paaticular mode of origin. 

It is by no means an objective of this papet it()) sugLf 

gest that graphic tecture is a criterion -of repmtoomeJltL 

On the contrary, it seems probable that the.t{eX'<tttl't.et.m'Ry 

be formed in any of at le·ast· 1i0>u:r:. way~: ~l J :By ~irnul;:.. 

taneous intergrowths not ~ eutecti'e(!:pV~ortJion~i~: (2) 

by eut~ctic crystal~i~~~Jip1:-: (3~ b1frunm.ixing 0f Sti>lid .,·-.. ,; :;; !;,;-; ~t) .-'i .. :,J __ ;.-f, ~i' ~_ .~ .·;,. .. ; 

· .M Gi lspp f J. L , 1 qc;>~i i}rites ~p; Ph · , ~ q ~ill~ <'l ¥jct of -nortb,ern ld~qo : 

Jour. Geology, vol. 35,.p. 8, 1927 , D . y; > •.'>A., Secondary origin of certain granites:: 

Am Jour.ScL 4tli er'. tbi.1ld;~~.!OO &fs 1rYt-'l- f.: .. 'J : ·r · •,, . 

. 36 Schaller, W. T.,,: 'l'.ne geJ!!~Si · · M>'91~ ~~gm~t~t . foFfl· r ~1 ~ :5th ser., 

vol. 10, p . 276, 1925. . . -

37 Aurousseau, M., Analyses of three Austr a>lian rocks: Linnearr Sdc.'· New South 

Wales Proc,, vol. 5l , p .. 623, 1926. See ;¥ ~ E' lco;t er, J. , op_ ..cj,t, 

38 Whitehead, W. L., The parage:qesis of certain sulpb,ide intergrowths: Ecom; 

Geology, vol. 11, pp. 1-13,' 1916! R-ogers, A.: F., 'The so-called gr'a~liic intergro.¥thl·b 

bornite and chalcocite: Econ. Geology 1 vol. 11, pp. 58!2;-59~,1 19,16. 9ui~d( ,F '! N'··rfl\ 

microscopic study of the silver ores: Econ. Geology, vol.12,pp. 313-314, 1917. ~~d-­

gren, Waldemar, Mineral deposits, atl ei:l., pp. 209, 926, New York~ 19'28,,P seird61 

eutectic tertur.es: Ec~., <;l;eoleg~ ~~J-. 1 f~~ .p.p., r-q,,_ 193(). Sc.lrw.l}tt}; G· .. , 1 ~ i It 

Park, c: F 1 jr .• :Pseudo-eutectie textlires:. ,Econ. Geology, vol. 25, .gp·. 65H63, 1930. 

Bastin, E. s 0' and o'iiier.si' 6titeK4!' ag r~ ations. of minefaas: 1ll ~ed;tGe(i! gy' ¥~1.~ pp.57(L; 57l);l93L , ,·· .. ' :'·t".. :· L~ 'jt' . ·,,( f:·) ·, ;·,;,'.;Tf 

39 Tyrell, G. W., The principles af.'-ettqlogy, p. 64, ~ew Yqrk, 1927. . 

40 Sugi, K'., on the granitic to k: o 't4i~i TsU:kuba distri6t and Thtiir itSS eidted 

injection rocks: Jap nese Jour~ Geelo/g¥fl.;tik'<t t~9~l'a ) vq · PJ? v firli'7t, 19:;39•· • ' 

41 Beskow, Gunnar, Soqra Storfjallet)m ·, i}.~li<?hen ~p:Plari<! ~ ein~ J!etrographische und geologische studte im zenf ai~nt TJil1d'es:. Skatici1nav'isbhenl H@cligebirges: 

Sveriges geol< .• <Underso)Glip.g ~s&9!!i l,·N Q; ~~ liJ ,\ oq if10 ~ :PJ.l,• 19 ;lq5, 19~7. 

42 Wells, .. ;A. K., aD:d :W,9oldrJ\!!).el. ~ %· 'ii~e rock ~ups .9f Jerse~ w'ith special 

reference t'o intrusive phenomena · ·. ~lt . z. 1 Gbologists lAss~ T roc . ..-woi. 42, p. 211, -· ·--~~..........._. ·-· ' ~~ - 1931. ' . ' ' ''i'Jlt ' ... ! ; j . . / . . '.0 ' 

43 Bastin, E. S., and others/ Eco'n'.' e~l gy, 'Vol. 26-,' p: 5'74; 19~1. · . 

u Vogt, J. H. L., op cit., 1903 .. Loewinson-~ssing,l·• anq Zem:~ ;'· ·· ·~ :.?"fl phyrartige Struktur und Eutekttk: Russ. k. mmeral. Gesell. VeJ;fi., .2tl s~ ··. ':8~~~ 

44, pp. 24-1-256, 1906. , r fi ·r 
REPLACEMENT ORIGIN OF ALBITE GRANITE NEAR SPARTA, OREG. 

solutions,45 and (4) by replacement. However, it is 

desirable to recognize that the texture is not in itself 

a valid criterion of eutectic crystallization. The 

writer believes that the evidence is strong that the 

texture of the albite granite near Sparta results, at least 

in very large part, from replacement. 

There are all gradations· between well-developed 

micrographic textures and irregular quartz intergr-owths with feldspar, such as are seen in Plate 22 D, 

with' -less and less regular development of the components, eventually passing to isolated qunrtz areas in 

feldspars that might, except for the associated phenomena, pass for mere inclusions. 

The venniform, lobate, and venous disposition of the 

quartz of the albite granite is characteristic, and all 

gradations from thin tongues of quartz in albite to 

stringers and wisps of albite in a "sea" of. quartz (pl. 

22, B, C; 23, A) are to be seen. These transitions are 

more and more striking the more albitic the rock. The 

fact that the lobes of quartz are dominantly oriented 

with their convexity toward the. feldspar is believed to 

be significant of replacement. (See pls. 19, A; 22, D; 

23, A.) Very similar quartz grains, apparently working their way in along boundaries between plagioclase 

crystals and corroding associated microperthite, have 

been interpreted as suggestive of replacement by Wells 

and Wooldridge. 46 

Lacroix 47 interpreted denticulate contacts of anorthite a.gainst the mafic minerals in the contact of the 

lherzolite of the Pyrenees ns due to replacement. 

Similar structures have been so interpreted by Shaub,48 

and the analogous orientation of lobate myrmekite 

toward n1icrocline has been almost uniformly interpreted as evidence of replacement.49 The feature here 

discussed differs from myrmekite in that plagioclase 

rather than potash feldsp~r ·is the host mineral, and 

quartz alone rather than a quartz-albite intergrowth is 

the replacing mineral, but the f-orms are strictly analogous. Such textures have been interpreted as due to 

replacement by Callaway 50 and GrovesY In mineragraphic work similar textures have been interpreted as 

evidence of replacement.52 

•5 Schwartz, G. M., Experiments bearing on bornite-chalcocite intergrowths: 

Econ. Geology, vol. 23, pp. 388, 395, 1928. 

46 Wells, A. K., and Wooldridge, S. W., The rock groups of Jersey, with special 

reference to intrusive phenomena at Ronez: G,eologists Assoc. Proc., vol. 42, p. 203, 

1931. 

•1 Lacroix, A., Les phenomenes de contact de la lherzolite et de quelques ophites 

des Pyrenees: Services carte geol. France Bull., vol. 6, No. 42, p 27, 1895. 

•s Shaub, B. M., A unique feldspar deposit near DeKalb Junction, N.Y.: Econ. 

Geology, vol. 24, p. 88, fig. 13, 1929. 

•B Fouque, F., and Michel-Levy, A., Mineralogie micrographique: Mem. Carte 

geol. France, p. 193, 1879. Seder holm, J .-J ., op cit., p. 135. Becke, F., op. cit., 

p. 382. Tronquoy, R., op. cit., p. 219-220. Tilley, C. E., The granite gneisses of the 

Southern Eyre Peninsula: Geol. Soc. London, Quart. Jour., vol. 77, pp. 87-88, 1921. 

6° Callaway, C., Can a diorite become an acidic gneiss?: Geol. Mag., dec. 4, vol. 2, 

pp. 220-233, 1895. 

61 Groves, A. W ., The heavy minerals of the plutonic rocks of the Channel Islands; 

2,Guernsey, Sark, and Alderney: Geol. Mag., vol. 64, pp. 462-464, 1927. 

62 Schwartz, G. M., Copper veins on Susie Island, Lake Superior: Econ. Geology, 

vol. 23, p. 768, fig. 5 (p. 766), 1928. Lindgren, Waldemar, and Creveling, J. C., The 

ores of Po~osi, Bolivia: Econ. Geology, vol. 23, p. 250, fig. 11 (p. 248), 1928. Lindgren, Waldemar, Pseudo-eutectic textures: Econ. Geology, vol. 25, p. 2, figs. 2-4, 

and elsewhere, 1930. 

In the descript,ive section of this paper attenti<:>n wa~ 

called to the presence of considerable · albite with ·.the 

habit to whieh the name "chessboard" (SchaehbiFett} 

albite has been given. It is pertinent that this va-rietYl 

of albite is eommonly interpreted as resulting from 

replacement. 53 In some oeeurrenees there is ·no evi...-

den~e of its being seeondary,54 but exeess minelfalii ers 

are even there regarded as having led to its fornration; 

The oecurrenee of this variety of albite, C<Ymmonly 11eJ 

garded as typieal of replaeement, lends some aclditilonal• 

support to the more direct evidenees of a seeonda:ry 

albitization of these roeks, though in view of Tilley's· 

eonelusion its intrinsic value as evidence is slight. 

The oeeurrenee of veinlets of albite penetrating' 

eraeks through all the other minerals (see pl. 22, B) i$1 

further evidenee of permeation of the rock by albitic -

solutions after its eonsolidation. 

The eorrelation between quartz and albite eontentJ 

on the one hand and eataelastie phenomena on the 

other has been eommented on as suggesting a connec.:.. 

tion between the two. If this eonneetion eame about 

beeause the breeciation furnished ehannels of aeeess 

for albitie silieeous solutions, the oeeurrenee of crystwlloblastie texture loeally in the albite granite is quite 

consistent with this meehanism, as such solutions 

would be favorable to reerystallization of the roek,5

& 

and when breeeiation eeased, or even where the roek 

was loeally sheltered during breeeiation, erystalloblastesis would be expected. 

MINERALOGIC EVIDENCE 

The remarkable poverty of the feldspar m calcic 

plagioelase (mueh of it being at least as sodie as 

Ab95An5 and aceompanied by little zoisite or other 

saussuritic product) must be regarded as casting suspieion upon any hypothesis of a purely igneous origin of 

the albite granite. 

As it is well known that the method of computing' 

the norm throws the maximum lime into anorthite it 

is noteworthy that even the norms of Nos. 3 and 4 

(p. 70) carry sodie oligoelase feldspars. Thus even if 

all the epidote now found in the albite granite were 

derived from original anorthite, the primary feldspar 

must have been elose to Ab90, on any reasonable assumptions of the distribution of lime in the amphiboles. 

A plagioelase melt of sueh eomposition would be in 

equilibrium with erystals of a composition near sodic 

sa Goldschmidt, V. M., Die Kontaktmetamorphose im Kristianiagebiete: Vidensk. Skrifter, I, Mat.-Naturv. Klasse, 1911, No. 1, pp. 301-302; Ubersicht der 

Eruptivgesteine im kaledonischen Gebirge zwischen Stavanger und Trondhjem: 

Idem, 1916, No. 2, pp. 68, 71, 78, 86. Becke, Friederich, Zur Physiographie der 

Gemengteile der Krystallinen Schiefer: K. k. Akad. Wiss., Mat.-Naturwiss. Klasse, 

Denkschr., Band 75, pp. 124-125, 1913. Grubenmann, U., and Niggli, P., Die Ge8-

teinsmetamorphose, I, pp. 435-436, Berlin, 1924. Andersen, Olaf, The genesis of 

some types of feldspar from granite pegmatites: Norsk geol. Tidsskrift, Bind 10, 

H. 1-2, p. 151, 1928. 

54 Tilley, C. E., The petrology of the granitic mass of Cape Willoughby, Kangaroo 

Island, pt. 1: Roy. Soc. South Australia Trans. and Proc., vol. 43, pp. 328-329, 19HI. 

55 Seder holm, J. J., On migmatites and associated pre-Cambrian rocks of southwest 

Finland: Corum. geol. Finlande Bull., vol. 12, No. 77, pp. 124-125, 1926. Tyrrell, 

G. W., The principles of petrology, pp. 252-256, New York, 1927. 
74 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1932-33 

andesine 56 and as such could be derived as a rest 

magma from consolidating diorite. Such a derivation 

would not account for the comparative poverty in 

potash, however, and there is evidence that the selective enrichment in sodic feldspar with respect to potassic feldspar is dependent upon hydrothermal influences. 

As long ago as 187 5 Credner 57 called attention to 

the fact that nearly pure albite is a good sign of hydrothermal action, and this ·has been recognized by many 

others since then. Schaller 58 has stated that it is 

likely that no feldspar more sodic than Ab95An5 is 

ever pyrogenic. Whether or not this generalization 

will hold, there can be no question tbat most feldspars so sodic are of nonpyrogenic origin, and consequently their occurrence here is suggestive, if no more, 

of a replacement origin. 

The b1otchy development of hastingsite in parts of 

the common hornblende of the albite granite also 

indicates attack by sodic solutions upon the common 

green · hornblende. The identity of the common 

hornblende with that of the quartz diorite indicates 

the close relations of the two rocks, and its blotching 

by hastingsite strongly suggests postmagmatic attack. 

This feature is paralleled by the formation of a 

"glaucophanelike" amphibole from common hornblende by circulating "late magmatic" solutions in 

a rock described by Colony. 59 

Other mineralogic evidence suggesting late magmatic or postmagmatic attack on the diorite to produce the albite granite consists in the widespread 

development of epidote and chlorite that is characteristic of the albite granite, in place of the usual 

pyrogenic mafic minerals, and especially the marked 

way in which the completeness of this substitution 

parallels the development of quartz and albite in 

the rock. Partly silicified and albitized rocks of this 

series ordinarily retain considerable common hornblende which, as the quantity of quartz increases, is 

altered to epidote and in part to small amounts of 

hastingsite. 

The blue quartz of the albite granite, which owes 

its color to minute needles of rutile (?), is remarkably 

different from the co]orless quartz of the quartz 

diorite. Many rocks of the transition series contain 

both kinds of quartz, which are readily distinguishable 

in hand specimens. The similarity in color of this 

quartz to that of many quartz nests in hydrothermally 

altered schist is striking. Although no importance 

could be reasonably ascribed to this similarity in 

itself, yet when it is considered in connection with 

the venous habit of much of the quartz and with the 

other evidences of hydrothermal rep]acement procM Bowen, N. L., The evolution of the igneous rocks, p. 34, Princeton, 1928. 

67 Credner, Herman, Die granitischen G!inge des slichsischen Granulit-Gebirges: 

Deutsch. geol. Gesell. Zeitschr., vol. 27, p. 179, 1875. 

68 Schaller, W. T., The genesis of lithium pegmatites: Am. Jour. Sci., 5th ser., 

vol. 10, p. 279, 1925. 

69 Colony, R. J ., The final consolidation phenomena in the crystallization of igneous 

rock: Jour. Geology, vol. 31; p. 173, 1923. 

esses, it appears significant. It is noteworthy that 

rutile, especiaJly in needle form, is commonly :regarded 

as of hydrothermal origin 60 and that it is the common 

titanium mineral in 1nany rocks rich in albite and 

quartz as was pointed out by Geijer 61 and Sundius.62 

SUMMARY OF MICROSCOPIC EVIDENCE 

The microscopic features strengthen the suggestion 

furnished by the field and chemical relation-s that the 

albite granite is a product of silicifie.atio:n and albitization of the quartz diorite in place. Features. suggesting a replacement origin of the albite gr~nite may,file 

summarized as follows: 

Textural features: 

1. Cataclastic and crystalloblastic features aFe correlative 

with quartz and albite content. 

2. The feldspars of the albite rock are partial pseudomorphs 

of those of the quartz diorite. 

3. The forms of some feldspars suggest corrosion of andesine 

and its replacement by albite. 

4. Myrmekite, limited to the albite granite, shows the 

existence of postmagmatic albitic solutions. 

5. Veins of albite cutting earlier minerals are also evidence 

of postmagmatic albitic solutions. . 

6. The lobate penetrative forms of the quartz of the albite 

granite suggest replacement. 

7. The micrographic texture of much of the albite g~anit~ 

is not inconsistent with a replacement origin. 

Mineralogic features: 

1. The remarkablepoverty of the anorthite molecule in the 

albite granite renders a pyrogenic origin improbable. 

2. Chessboard albite suggests a hydrothermal origin. 

3. The blotchy development of hastingsite in parts of the 

hornblende of the albite granite suggests a later per .. 

meation of the rock by soda-rich solutions. 

4. The widespread occurrence of epidote rather than other 

mafic minerals in the albite granite suggests hydTothermal processes. 

5. The notably blue eolQr oi the quartq of the. &lbite granite 

is suggestive of bydr~ hennal origip ~ 

No one of the featlU'ea just- enume:ra.ted can -be 

considered cop.clusive in it.&elf e>f the Gt>r;reotness of the 

hypothesis advaneed. N evfi}rth~less, -their cu.mulative 

force is great, and when taken in conjuncti{)n with the 

field relations and chemistry of the rocks they have 

led to the formulation of the replaceme:fl ' ~Qthesis. 

EVJDENCE QF Til~ VARIATION DIAGRAM 

On the varia.tion diagram of Figure 2 are plotted 

the chemical compositions of the analyzed roeks. . For 

con1parison, a "normal" differentiation series Bowen's 

weighted diagram of the Katmai volcanic roeks, an'tl 

a soda granite series, -Goldschmidt's. 'fOpd~rit-e ... 

Trondhjemite Stamm,':·, .ar:e plotted ·on the' same 

diagra1n. . 

6o Miigge, 0., in Rosenbusch, H., Mikroskopiscbe Pl\ysiogr!).phie qe:q>etrographische wichtigen Mineralien, Band 1, Zweite Halfte, 5th ed., pp. 94-95, 1~27. Winchell, A. N., Elements of optical mineralogy; pt. 2, p. 53, New York, 1927. Gillson, 

J. L., and Kania, J. E. A., The genesis o{ the emery deposits·ne8{ P~eksll;\Il, N.Y.: 

Econ. Geology, vol. 25, p. 515, 1930. · · • 

61 Geijer, Per, Masugnsbyf!Utens geolQ~: Sveriges geol. Unq(l.rsQI\ning ~rsbo~ 

vol. 22, ser. C, No. 351, p. 37, 1928. 

62 Sundius, N., On the differentiation of tl\e alkaUes in aplites and tlPlitic gr~ni~;,. 

Sveriges geol. Underookning Arsbok, vol. 19, ser. C, No. 336, 1925. _ · 
REPLACEMENT ORIGIN OF ALBITE GRANITE NEAR SPARTA, OREG. 75 

Some check upon the replacement hypothesis is 

furnished by this variation diagram. If the hypothesis 

is correct, there should be a tendency for the albitic 

rocks to show compositions intermediate between that 

of the quartz diorite and that of some pegmatitic 

"rest m.agma," and the plotted oxides of the several 

rocks should approach lines representing mixtures of 

f?Uch pegmatitic liquid and the original quartz diorite. 

This tendency should be only approximate, of course, 

because there is likelihood of selective replacement of 

some minerals with consequent variation from a 

lines connecting the values of the other oxides in the 

quartz diorite with values of the same oxides in the 

most siliceous albite granite were projected to zero. 

The line falling farthest to the right is that of Fe20a, 

which falls to zero at 84 per cent Si02. If the intermediate rocks were the result of simple mixing of the 

two end . members, the composition of the siliceous 

member would be fixed by the oxide falling to zero 

first rather than last, but in view of the possibilities of 

selective replacement, the curve for iron oxides is 

believ:ed to be more representative than that for magnesia. It is cJear from the dia- lO% -.----------------r------,------.--------10% 

gram that KzO is about constant, with a slight tendency 

to increase. It is therefore 

---- arbitrarily assumed that the ~~.'2.() ..,----- -

5'7o- N~- ~--- d) NazO -<>5% pegmatitic juice mixing with 

~ 

--~-~-~-~;-~-~~~~~-~-~-~-~-;::::~~;~;~==------ -- NazO --- 84 ~~~fu~~~~ per cent of Si02 and 1.50 

.., ... .:.-V-.?-° KzO -----=--===--====-=-=--- KzO percentofK20, the rest be~g 

--~o the soda and alumina necesSi02 55% 60% 65% 70% 75% 

r~ ;.,] (!) 

~~ ~~] C':O_ A/z 0 3 a.. !i!" 

Alz.03--=-- ------------ ---------AGo;- -...::::..:::: --- -----........... 15%- -------- ... ---- ' ............. 

---- "-. 

10%-

80% 

-5'7c 

sary for albite and orthoclase. 

This is computed to the following composition: 

Composition of assumed reacting 

liquid 

Si02--------------------- 84.00 

Al20a------------------- - 9. 63 N~O_______ ____________ 4. 86 

K20 ___ ----------------- - 1. 50 

Mineral composition: 

Quartz_ -. ___________ _ 

Albite ______________ _ 

Orthoclase __________ _ 

99. 99 

50. z 

40. 9 

8. 9· 

Broken lines are drawn on 

the diagram connecting the 

points representing the oxides 

of the quartz diorite with 

the corresponding values for 

Si02 55% so% 65% this hypothetical pegmatitic 

-Sparta series ---Tr.ondhjem series liquid. 

FIGURE 2.-Variation diagram showing chemical composition of quartz diorite and albite granite, with two intermediate It is obvious that the 

rocks, contrasted with the weighted variation diagram of the Katmai rocks after Bowen (Evolution of the igneous variation curves of all the 

rocks, p. 119, fig. 36, Princeton, 1928) and a variation diagram constructed from the analyses of the opdalite-trondhjemite series given by Goldschmidt CUbersicht der Eruptivgesteine im kaledonischen Gebirge zwischen Stavanger oxides except CaO a p p r 0 xiund Trondhjem: Vidensk. Skrifter, I, Mat.-Naturv. Klasse, 1916, No.2, table opp. p. 140) mate much more closely to 

straight-line relation. Inasmuch as the "normal" ' the straight lines than to the lines of either the normal 

course of differentiation itself tends toward a pegmatitic series or the . opdalite-trondhjemite series. Even the 

end product, the test of the hypothesis must be a CaO curve shows a slight tendency in the same 

closer approach of the intermediate rocks to a straight- direction. 

line relation between the quartz diorite · and the postu- The marked differences between the curves of the 

lated pegmatitic end stage than to the curves of the opdalite-trondhjemite series and those of the normal 

normal series, or to the curves of the opdalite:..trondh- series render deductions as to origin from the variajemite series, which are conceded to be governed almost tion diagram alone of doubtful value. The similarity 

wholly by magmatic processes. of the curves of the N o'rwegian rocks and those of the 

As the microscopic evidence suggests addition of Oregon rocks near the siliceous end would suggest on 

only soda, potassa, and silica in noteworthy quantities, this basis that the Norwegian series contains similar 
76 SHORTER CONTlHB"UTIONS TO GENERAL G,E~hftG'T " i 932-33 

replacenwnt rocks. There is, indeed, some suggestion 

of local replacement phenomena in these more siliceous 

rocks 63 leading to albite coating of oligoclase and the 

development of hornblende after augite and of chessboard albite, but the presence of oligoclase as the 

major plagioclase rather than albite, and of "antirapikiwi" rims of orthoclase about cores of oligoclase 

in some of the typical trondhjemites seems to preclude 

any quantitatively important replacement in them. 

For these reasons it would be decidedly unwarranted 

to stress the testimony of the variation diagram, but 

it seems quite justifiable to point out the accordance 

between ,the actual curves and those to be expected 

under the simplest conditions of the replacement hypothesis. As corroborative evidence the variation diagram may be given considerably .more weight than it 

could claim intrinsically. 

SOURCE OF THE ALBITIZING SOLUTIONS 

If the conclusion that the albite granite owes its 

present composition to postmagmatic silicification and 

albitization is sound, one is immediately led to consider the possible sources of such solutions. The 

albitic and siliceous solutions may be thought of as 

originating (1) from near-by portions of the solid 

diorite, (2) from the intruded greenstones, (3) as restmagma solutions of local source, (4) as hydrothermal 

solutions of deep-seated origin. These possible sources 

are considered below. 

SOLUTIONS DERIVED FROM THE SOIID DIORITE BY 

METAMORPHISM 

Albitization in spilitic rocks has been attributed by 

Sundius 64 to an exchange of soda for lime in one part 

of a rock body for a reciprocal replacement in an adjacent part, the composition of the mass as a whole remaining essentially unchanged during the metamorphism. The hypothesis was developed to explain the 

marked local variations in the quantities of albite and 

epidote in some of the Kiruna greenstones. There can 

be little doubt that such a process is locally effective. 

In the Sparta rocks, however, it can not be admitted 

as important, except, perhaps, in respect to the albite 

granites in the southern part of the Baker quadrangle, 

where they occur in saussurite gabbro. There is no 

sign that the near-by diorites have reacted with the 

albite granites, leading to a concentration of lime minerals in the diorites and of soda in the albite granites. 

The albite granites themselves are decidedly poor in 

dark minerals, so that the calcic reciprocal of the albitic 

rocks must, under this hypothesis, be sought in the 

adjacent diorites and gabbros. These rocks, however, 

are only moderately saussuritized: the small amounts 

of epidote and zoisite they contain can well have been 

63 Goldschmidt, V. M., op. cit. (1916), pp. 68, 71, 78, 86. 64 Sundius, Nils, Zur Fraga Albitisierung: Geol. Foran. Forb., vol. 38, pp. 446 et 

seq., 1916. 

supplied locally and are quantitatively altogether disproportionate to the large masses of albite gra:ni'te in 

the area, except, as just stated, in the southern'" part 

of the Baker quadrangle. 

The same argument applies against an assumption 

that the sodic and siliceous solutions were derived by 

leaching from the adjacent diorites and gabbros during metamorphism. The feldspars .of · the diorites are 

so slightly altered that it is extremely unlikely that 

they could have supplied sufficient silica and ·soda to 

bring about the observed .alterations of the alli>itic 

rocks, even were all the soda and silica that had b~en 

set free during saussuritization to be carried ' away. 

However, the well-known tendency in such changes is 

to fix the soda as albite, and this has certainly occurred 

in the saussurite of these rocks. The albite granites in 

the saussurite gabbro, in the southern part of the 

Baker quadrangle must again be excepted from those 

near Sparta. 

SOLUTIONS DERIVED FROM THE INTRUDED GREENSTONES 

The localization of the larger of the albite granite 

masses in the belt of outcrop of the Permian greenstones that are dominantly keratophyres. and spilites 

suggests that a genetic relation may exist between 

them. This possibility is strengthened by the common 

association of soda granites and spilitic greenstones 

elsewhere, notably in the Caledonian mountains of 

Norway 65 and in the British Isles,66 which has led 

Dewey and Flett to consider the soda granites a part 

of their "spilitic suite." 

A review of the literature pertaining to Qther da 

granites, as summarized in a later par-t of this paper, 

seems to show, however, th~t they are nq.t.-limited to 

spilitic associations (as indeed is de onstrated by the 

occurrences in gabbro many. miles from the nearest 

spilitic rocks in this s~m ' regio_n), .... n~r are tiiey 

characteristically the products of mag;t:aas with no~ 

tably high primary soda cont nt. 

If it is considered that the albitization of the quartz 

diorite is due to endomorphism consequent upon its 

intrusion into the older albitic greenstones, one· would 

expect a rather close limitation of the alteration to 

the vicinity of the contacts. This is not folJ.Ud~ 

however; some of the albite granite bodies are ~parated from the greenstones by consideraR~e, :) 9f 

unalbitized diorites. The large size of some bqdies 

of albite granite is also unfavorable to 'S\19h:"a tri :ri.§fer 

of soda and silica from the intruded intd :he ti ive 

bodies, for the few examples noted of ~u P Iie >' f host rock upon intrusive are generally c1l ~a!d t~n-ied 

by comparatively narrow zones of alter tiori. '' ~ · I ,_ ~ t 1 

ss Goldschmidt, V. M., Ubersicl;lt d~J; i~fUlptivge;ste ne iql ka)eqqqisc,Pei};(JE;Jl:)inge 

z':iscben Stavanger und 'J'rondbj~~=~ y~<;Im ~. Skr fter, ~ tur': . ~lass~, 

Bind1,No.2, 1916. ' '' ''· -· '' '· ·•."· 1

' •- '' I, 

66 Dewey, Henry, and Flett, J. S., Qn.some ;Brillish pilJo l;lY~S' d tl).!~ c~s 

associated with them: Geol. Mag., dec. 5, vol. 8, pp. 202-2?9, l~ tf l , ! :t · ,. i ·-

,·,, • : J. ;. '•t ~· 
REPLACEMENT ORIGIN OF ALBITE GRANITE NEAR SPARTA, OREG. 

The fact that the intrusive rocks are younger than 

the greenstones obviously disposes of any possibility 

that solutions derived by autolysis of the spilitic 

greenstones, according to the . hypothesis of either 

Dewey and Flett 67 or 'Eskola,68 could have brought 

about the albitization of the diorites. . 

This is not an. appropriate place to discuss the question of the spilites, but it may be that their association with soda granites in some localities, which led 

Dewey and Flett to regard the two as comagmatic, 

may .on the contrary, be due to the action of similar 

albitizing solutions upon both rocks. 

At least some of the albite granites of the Caledonian 

Mountains of Lapland are · separated in age by a 

period of mountain building from the earlier spilitic 

rocks (keratophyres) with which they are geographically associated. Beskow 69 can see no other relation 

between them than that existing between different 

bodies as a result of the action of similar differentiation 

processes at different geologic periods. The relations 

ill eastern Oregon are similar. The local albitequartz masses in gabbro many miles from the nearest 

spilitic volcanic rocks and separated from them by a 

full geologic period seem t.o point to the correctness of 

Beskow's view. 

LOCAL REST-MAGMA SOLUTIONS 

It is the universally recognized result of magmatic 

crystallization to concentrate in a low-freezing residual 

magma larger proportions of the original alkalies and 

silica than are to be found in the magma· as a whole. 

The selective enrichment of soda with respect to 

potassa is considered in a later section of this paper. 

Unquestionably this is the common origin of the sodic 

and siliceous mesostasis of many quartz diabases. 

Many of these diabases carry groundmasses whose 

composition approximates that of albite granites. 

Local conditions may well effect slight differences in 

the concentrations of such residual magmas or solu- · 

tions, thus bringing about the production of some 

albite and quartz as the final residues in parts of a 

crystallizing rock. Doub~less it is this process· which 

commonly leads to the formation of myrmekite and 

other synantetic products. The quantitative factor 

in the ·alterations of the Sparta rocks is believed 

to eliminate such a local process as the direct cause 

of their differences. 

HYDROTHERMAL SOLUTIONS OF DEEP-SEATED ORIGIN 

If, however, it is recognized that there is a common 

tendency toward the formation of such solutions rich 

in soda and silica, as exemplified in the micropegma67 Idem, pp. 204-205. 

68 Eskola, P ., On the petrology of eastern Fennoskandia; I, The mineral develop. 

ment of basic rocks in the Karelian formations: Fennia, vol. 45, No. 19, pp. 89-91, 

1925. 

69 Beskow, Gunnar, Sodra StorfjlUlet im sudlichen Lappland, eine petrographische 

und geologische Studie im zentralen Teil des skandinavischen Hochgebirges: 

Sveriges geol. Undersokning Arsbok 21, No.5, ser. C, No. 350, p, 298, 1927, 

titic groundmasses of many quartz diabases, in: the 

aplites: associated with many diorites and granodio 

rites, and in the pegmatites of nearly all siliceous rock8, 

it becomes decidedly significant that the albite granite 

is appf!,rently confined to the more brecciated parts of 

the didritic intrusive bodies, that it is veined by quartz 

and al~ite, and that its amphiboles are blotched With 

sodic 1alteration products. These features are. all 

compatible with a theory that would derive . the albite 

granite from gabbro and diorite of the types of the 

adjace~t rocks through the replacement of much of 

their lljlass by quartz and albite deposited from hydrotherm~ solutions circulating through breccia zones. 

If the course of crystallization of a magma leads to the 

produqtion of such a sodic and siliceous rest magma, 

it is entirely possible that such magmatic residues 

might !he expressed from the main igneous body and 

penetrate the earlier solidified apophyses along breccia 

zones, , bringing about therein a considerable albitization rand silicification. The solutions were, orr this 

hypothesis, presumably derived from deeper levels in 

the igneous mass and were forced through the earlier 

solidifi~d diorite by orogenic pressure. 

SELECTIVE ENRICHMENT OF SODA IN HYDROTHERMAL SOLUTIONS 

Accqrding to the theory, of crystallization differentiation: there should be, at least in "dry" magmas, no 

selective enrichment of soda with respect to potash in 

the later stages of magmatic crystallization.70 However, Goldschmidt, 71 as well as Bowen, has shown that 

a high pontent of water in a magma may, through briTiging about an early separation of biotite, lead to the 

suppre~sion of potash feldspar in the low-temperature 

derivatives. The theory has likewise been exploited 

by V agt. 72 Biotite, though unquestionably a truly 

niagm~tic mineral in most occurrences, is by no means 

. formeq only under magmatic conditions but extends 

into the hydrothermal stage. In so far as it is hydrothermal, it would, like sericite, which is always hydrotherm~l, tend to impoverish the residual magmatic 

extracts in potash. 

Goldschmidt's theory has been elaborated in considera-ble detail by Beskow,73 who has strongly urged 

its adequacy in producing soda enrichment in the later 

stages : of magmatic development. However, he believes 7

( that the albite-epidote rocks of the "helsinkite 

facies' ~ owe their special enrichment in albite to the 

instability of calcic plagioclase at comparatively low 

tempet atures. In hydrous environments the unmixing of the plagioclase, which under normal conditions 

10 Bowe~, N. L., op. cit., p. 132. 

71 Goldschmidt, V. M ., Stammestypen der Eruptivgesteine: Vidensk. Skrifter, 

I, Mat.-Naturv. Klasse, 1922, No. 10, pp. 6-7. 

72Vogt, r.t'horolf, Sulitelmafeltets geologi og petrografi: Norges geol. Undersokelse, 

No. 121, p. 496, 1927. 

73 Beskqw, Gunnar, op. cit., pp. 256-264. Beskow and Goldschmidt do not regard 

the forma,tion of biotite as extending into the hydrothermal stage. In so far as it 

does, it cooperates with sericitization in depleting the solutions in potassa. 

H Idem~ pp. 195-214. 
78 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1932-33 

is only potential, proceeds readily with the production 

of epidote (or in special cases, amphibole) and the freeing of albite. Mild hydrothermal alteration thus 

results in saussuritization, but higher water concentrations may lead to the formation of large bodies of 

low-temperature hydrous magmas parental to the 

helsinkites. Beskow does not apply this mechanism 

to the production of hydrothermal solutions per se, 

but to the writer it seems an entirely feasible system. 

V ogt 75 has also regarded the late Inagmatic and early 

postmagmatic reactions in a granite as leading to the 

fixation of potassa in muscovite, which frees soda and 

lime. By reaction with potash feldspar myrmekite is 

formed, and the additional potash set free is, at least 

locally, fixed in mica, so that the only alkali thrown 

into the residual solutions is soda. Silica is of course 

f~eed with the soda, thus producing at a late stage 

sodic and siliceous solutions set free from the solid 

granite. These solutions effect contact alteration of 

the adjacent country rocks, which, according to Vogt, 

show that they have received additions of soda, lime, 

and silica. This "leaching of alkalies" also accounts, 

in Vogt's opinion, for the common occurrence of 

normative corundum in Inica granites. 

Tilley 76 has considered it likely that highly albitic, 

mineralizer-rich liquids may result from the selective 

crystallization of potash feldspar from a rest magma 

in which both potash and soda were originally present 

in approxin1ately equal quantities. 

Thus the late deposition of albite rather than potash 

feldspar from hydrothermal solutions may be due not 

to absence of potassa in the solution but to the stability 

ranges of the feldspars, albite being the stable one at 

low temperatures. According to Grubenmann and 

Niggli,77 where both alkalies have been enriched during 

contact metamorphism, it is common to find the potash 

enrichment older than the soda enrichment. The 

replacement of microcline by albite in the later stages 

of pegmatite formation is clear evidence of the same 

fact. 78 

That solutions capable of causing albitization are not 

confined to pegmatites is amply demonstrated by the 

widespread occurrence of myrmekite, by albite impregnation in contact metamorphism/9 e$pecially in adi75 Vogt, Thorolf, op. cit., pp. 524-525. 

76 Tilley, C. E., op. cit., pp. 335-337. 

77 Grubenmann, U., and .Niggli, Paul, Die Gesteinsmetamorphose, I, p. 293, Berlin, 

1924. 

78 Brogger, W. C., Die Mineralien der Syenitpegmatitgange der Siidnorvegischen 

Augit- und Nephelinsyeuite: Zeitschr. Kryst. Min., vol. 60, p. 167, 1890. Schaller, 

W. T., op. cit., p. 279. Hess, F. L., The natural historyofthepegmatites: Eng. and 

Min. Jour., vol. 120, pp. 289-298, 1925. Landes, K. K., The paragenesis of the 

granite pegmatites of central Maine: Am. Mineralogist, vol. 10, pp. 371-374, 1925; 

Sequence of mineralization in the Keystone, S. Dak., pegmatites: Am. Mineralogist, vol. 13, p. 552, 1928. Anderson, Olaf, The genesis of some types of feldspar 

from granite pegmatites: Norsk geol.Tidskr., Bind 10, pp. 204--205, 1928. 

79 La Croix, A., Les pbencim(mes de contact de Ia lherzolite et de quelques opbites 

des Pyrenees: Service carte geol. France Bull., vol. 6, No. 42, pp. 84-86, 93, 99-100, 

107,125-133, 1895. Goldschmidt, V. M., Die Kontaktmetamorphoseim Kristianiagebiete: Vidensk. Skrifter, I, Mat.-Naturv. Klasse, 1911, pp. 36, 57-58, 300, 312-313; 

idem, 1916, No. 2, p. 93. 

noles,80 and by the common occurrence of postmag--

matic albitization both in granitic rocks and in 

basic or intermediate intrusive and extrusive rocksY 

Some of these alterations are on a scale comparable 

to that shown in the Sparta rocks. 

Esko]a 82 states that the normal course of crystallization should produce a segregation of alkali silicates 

and water in the magmatic residue at the lower temperatures and, without discussing the fate of the potash 

concentrate, ·regards the common occurrence of albitization as a result of this alkaline enrichment of the rest 

magma. Although Eskola is quite logical in regarding 

delessite and serpentine, which usually accompany 

this albitization, as low-temperature members of the 

mafic reaction series, most writers regard these minerals 

as diagnostic of hydrothermal rather than magmatic 

processes. At any rate, as Eskola has pointed out, 

there is no reason why ·such residual magma extracts 

should not separate from the main magma body and 

act upon "consolidated portions of the same rock mass 

or even adjacent rocks." Such extracts, according to 

the theory here developed, were responsible for the 

alteration of the gabbro and quartz diorite to albite 

granite. 

ALBITIZATION IN OTHER GRANITIC ROCKS 

Although large-scale albitization such as is postulated by the hypothesis here advanced for the origin 

of the Sparta rocks has not, so far as known to the 

writer, been previously suggested, the occurrence of 

similar phenomena on a smaller scale is widespread, 

and the process of late albitization has been recognized 

in several places in recent years. Holmquist 83 lias 

described corroded basic feldspars surrounded by 

albite in the Filipstad granite of Sweden. Phillips 84 

has described albitization in a Shetland dike. De 

Lapparent 85 has described albitization (regarded by 

him as magmatic) in some microgranites. Tronquoy,8& 

so Teall, J. J. H., Britisbpetrography, pp. 219-221, London, 1888. Hutchings, W. 

M., An interesting contact rock, with notes on contact metamorphism: Geol. Mag., 

dec. 4, vol. 2, p. 130, 1895. Bowen, N. L., Diabase and granophyre of the Gowganda 

Lake district, Ontario: Jour. Geology, vol 18, p. 664, 1910. Milch, L., Uber Adinolen und Adinolescbiefer des Harzes: Deutsch. geol. Gesell. Zeitschr., vol. 69, pp. 349-

486, 1917. Gillson. J. L., op. cit. (1927), p. 8. 

81 Bailey, E. B., and Grabham, G. W., Albitization of basic plagioclase feldspars: 

Geol. Mag., dec. 5, vol. 6, pp. 2ro-256, 1909 .. Dewey, Henry, and Flett, J. S., On 

some British pillow lavas and the rocks associated with them: Geol. Mag., dec. 5, 

vol. 8, pp. 202-209, 241-247, 1911. Cox, A. H., The geology of the district between 

Abereiddy and Abercastle: Geol. Soc. London Quart. Jour., vol. 71, p. 330, 1915 

Spencer, A. C., The Juneau gold belt, Alaska: U.S. Geol. Survey Bull. 'lB'l, pp.l01, 

11 1, 1906. Knopf, Adolph, Geology of the Berners Bay region, Alaska: U. S. Geol. 

Survey Bull. 446, pp. 32-34, 1911; The Eagle River region, southeastern Alaska: U. S. 

Geol. Survey Bull. 502, pp. 37-41, 1912. 

s2 Eskola, Pentti, On the petrology of eastern Fennoskandia, I, The mineral development of basic rocks in the Karelian formations: Fennia, vol. 45, No. 19, pp. 89-92, 

1925. 

83 Holmquist: P. J., Studien iiber die Granite von Schweden: Geol. Inst. Upsala 

Bull., vol. 7, p. 171, 1906. 

84 Phillips, F. C., Note on a riebeckite-bearing rock from the Shetlands: Geol. 

Mag., vol. 63, pp. 72-77, 1926. 

85 De Lapparent, J., Etude comparative de quelques porphyroldes fran~;aises: 

Soc. fran~;aise mineralogie Bull., vol. 32, pp. 243-263, 1909. 

86 Tronquoy, R., Contribution a l'~tude des gites d'etain: Soc. fran~;aise ·mineralogie Bull., vol. 35, p. 334, 1912; Origine de Ia myrmekite: Idem, p. 222. 

I, 
REPLACEMENT ORIGIN OF ALBITE GRANITE NEAR SPARTA, OREG. 7!9 

Colony,87 and Sugi 88 have also reeognized late magmatic albitization. Albite replacement of microcline 

is regarded by Suter 89 and Niggli 90 as a consequenee 

of the low temperature-stability range of albite rather 

than of any material difference in the concentration of 

soda with respect to potassa. Pflugshaupt 91 has 

thought that the process is advanced by pressure. 

Horwood and Wade 92 have referred the nJbite 

feldspar of the Orange Grove granite of the Transvaal 

to secondary alterations of original oligoclase. 

The masterly researeh of Thomas 93 on the igneous 

centers of Ardnamurchan contains numerous records 

of albitization of the intrusive rocks. Among them is 

the alteration of the gabbro and quartz gabbro west 

of Faskadale Bay,94 where the basic plagioclases are 

all inore or less albitized and the augite is altered to 

hornblende. In places the rocks contain a groundmass of quartz and alkaline feldspar, rich in apatite. 

The alteration may be due to an associated intrusion 

of granophyre. In another locality a hypersthene 

gabbro shows marginal facies much acidified by a 

partial magma, presumably derived from the hypersthene gabbro itself, which permeates the border zone 

irregularly. Locally it makes the whole rock a 

granophyre; elsewhere it merely forms granophyre 

patches in the gabbro.95 The gabbro feldspars are 

partly re~orbed ·and altered to oligoclase..;albite. 

Apatite is plentiful, and tourmaline occurs locally, 

testifying to the presence of mineralizers. "Acid" 

veins of similar composition cut the outer margin 'of 

the gabbro. They carry irregular quartz of granophyric habit but not obvious micrographic texture. 

The illustrations 96 resemble textures seen in the 

Sparta rocks. 

At another locality eucrite is altered by an "acid" 

partial magma, with the development of biotite. 

An "acid" mesostasis was observed in nearly all specimens and in many constitutes a considerable part of 

the rock. 97 It then forms turbid and in places grttphic 

perthitic feldspar-quartz intergrowths, with abundant 

apatite, which attack, corrode, and replace the basic 

feldspars with albite. Albitic fringes surround basic 

87 Colony, R. J., Final consolidation phenomena in the crystallization of igneous 

rocks: Jour. Geology, vol. 31, p. 173, 1923. 

88 Sugi, K., On the granitic rocks of the Tsukuba district and their associated injection rocks: Japanese Jour. Geology and Geography, vol. 8, p. 60 and elsewhere, 

1930. 

F9 Suter, Hans, Zur Petrographie des Grundgebirges von Laufenburg und Umgebung: Schweiz. min. pet. Mitt., Band 4, pp. 314-317, 1924. 

oo Niggli, Paul, Versuch einer natiirlichen Klassifikation der im weiteren Sinne 

magmatischen Erzlagerstatten: Abh. prakt. Geologie und Bergwirtschaftlehre, 

Band 1, pp. 11-13, 1925. 

91 Pflugshaupt, Paul, Beitrage zur Petrogr'hphie des ostlichen Aarmassivs: Schweiz. min. pet. Mitt., Band 7, p. 348, 1927. 

92 Horwood, C. B., and Wade, A., The old granites of Africa: Geol. Mag., dec. 5, 

vol. 6, pp. 549-554, 1909. 

93 Richey, J. E., and Thomas, H. H., The geology of Ardnamurchan, Northwest 

Mull and Coli: Scotland Geol. Survey Mem., 1930. 

94 Idem, p. 147. 

• 9s Idem, p. 227. 

oo Idem, fig. 3Qa, p. 229. 

97 Idem, p. 325. 

feldspars. Hornblende and biotite have developed at 

the expense of augite. The albitic fluid seems :to follow 

shatter cracks in the minerals. Bending and breaking 

of twin larriellae of the calcic plagioclase is always followed by albitization. Both phenon1ena are attributed 

by Thomas to the pressure exerted by the crystallization of a volatile-charged acid magma. Gradations 

occur from little or no acid material in the gabhro to 

little gabbro in a mass of acid material. 

Except for the Shetland, Ardnamurchan, and 

Transvaal nocks, none of the rocks described by these 

workers are highly albitic; nevertheless, . the widespread occurrence of very sodic feldspars associated 

with replacement phenomena in other rocks indicates 

how commonly, though on SO much sn1aller a scale, the 

processes appealed to in explaining the 'origin of ·. the 

Sparta rocks have been operative. 

OTHER ALBITE GRANITES 

Rpcks having the composition of typical albite 

granites have been described from occurrences in many 

parts of the· world and ·in . association with many kinds 

of other rocks. It is certain that, whatever may be true 

of some of these rocks, there is no suggestion that a 

primary sodic magma is necessary for their origin. 

Such a magma is, of course, unnecessary for other 

soda-rich siliceous rocks, many of 'which have , originated from normal sub alkaline rocks. For instance, the 

alkaline granites of eastern Massachusetts 98 and the 

soda-rich granites of the Riesengebirge 99 are both supposedly derived from subalkaline magmas .. Siinilarly, 

the trondhjemites of Norway have been regarded as 

derivatives of normal gabbroid magma. 1 · · 

FIELD ASSOCIATIONS 

Albite granites and albitites are known . in association with dioritic and more basic intrusive ro,cks in 

the Sierra Nevada, 2 Czechoslovakia, 3 ·Victoria, 4 ·Wales, 5 

British Columbia, 6 and Nevada. 7 · They occ:ur in 

98 Loughlin, G. F., and Hechinger, L.A., An unconformity in the Narragan~ett 

Basin of Rhode Island and Massachusetts: .Am. Jour~ Sci., 4th ser., vol. 38, p. 55, 

1914. 

99 Milch, L., Beitrage zur Kenntniss der gl-anitischen Gesteine des Riesengebirges: 

Neues Jahrbt, Beilage-Band 15, pp. 17G-l'i2, 1902. See also paper on adinoles previously cited, where albitic differentiates are shown to be normal products of subalkaline magmas. 

1 Goldschmidt, V. M., Stammestypen der Eruptivgesteine: Vidensk. Skr~fter~ 

I, Mat.-Naturv. Klasse, 1922; No, 10, pp. 6-7, Vogt, Thorolf, Sulitelmafeltets 

geologi og petrografi: Norges geol. Undei:sokelse, No. 121, p. 496, 1927. · 

2 Turner, H. W., The granitic rocks of the Sierra Nevada: Jour. Geology, vol. 

7, pp. 155-156, 1899. Reid, J. A., The east country of the Mother Lode: Min. 

and Sci. Press, vol. 94, pp. 279-280, 1907. . . 

3 Hinterlechner, K., and Von John, C., Uber Eruptivgesteine ausdem 'Eisengebirge in Bohmen: K.-k. geol. Reichsanstalt Jahrb., vol. 59, pp. 134--138, i909. · 4 Howitt, A. W., The rocks of Noyang: Roy·. Soc. Victoria Trans., ~ol. 2b; pp. 

4o-48, 1884. 

5 Thomas, H. H ., and Jones, 0. T., On the pre-Cambrian rocks of Brawdy, 

Hayscastle, and Brimaston: Geol. Soc. London Quart. Jour.; vol. 68, pp. 387-388, 

1912. 

6 McCann, W. 1S., Bridge River Map· area: Canada Geol. Survey ·Me:m. J30, 

p. 67, 1922 . 

1 Ransome, F. L., Notes on some albitite dikes from Nevada: Washington Acad. 

Sci. Jour., vol. 1, pp. 114-118, 1911. 
80 SHORTER · CONTRIBUTIONS TO GENERAL GEOLOGY, 1932-33 

association with subalkaline granite in the Riesengebirge,8 in Finland,9 in Sweden,10 in the Transvaal, 11 

in G~orgia/2 and in South Australia.13 

Rocks with the composition of albite granite occur 

with diabase in Ontario/4 Scotland/5 and Sweden. 16 

They are associated with sodic felsites in Ireland, 17 

Wales, 18 and Scotland 19 and with borolanite in 

Scotlan9..20 

Hogbom describes granophyric albite granite as a 

border facies of ordinary granite against sodic leptites. He regards it as due to contamination.21 

MINERALOGICAL AND TEXTURAL FEATURES 

Despite the diversity of rock associations in which 

these rocks are found, they have many features in 

common. Among the!TI is the very frequent occurrence of epidote either as the sole dark mineral or as 

the . predominant one. The helsinkite of Finland, 22 

the soda granite porphyry of the Sierra N evada/3 and 

the albite granites of Georgia,24 the Transvaal/5 

Switzerland, 26 Sweden, 'A7 Czechoslovakia, 28 Scotland,29 

and the Shetlands 30 all carry epidote as either the 

sole or dominant mafic constituent; chlorite, also a 

low-temperature hydrous mineral; is the chief mafic 

8 Milch, L., op. cit., pp. 17Q-172. 

9 Eskola, Pentti, Petrology of the Orijarvi region: Comm. geol. Finlande Bull., 

vol. 8; No. 40, 1914. Makinen, Eero, Pre-Cambrian geology of central Osterbotten 

in Finland: Comm. geol. Finlande Bull., vol. 9, No. 47, pp. 143, 146, 1916. 

10 Geijer, Per, . Masugnsbyfaltens geologi: Sveriges geol. Undersokning Arsbok 

22; No. 1, ser. C., No. 351, pp. 36-38. 1928. Sundius, N., On the differentiation of 

the alkalies in aplites and aplitic granites: Sveriges geol. Undersokning Arsbok 

19, No.3, ser. C, No. 336, 1925. 

u Horwood, C. B., and Wade, A., op. cit., pp. 549-554. 

12 Watson, T. L., Granites and genisses of Georgia: Georgia Geol. Survey Bull. 

9A, pp. 76-77, 1902. 

1s Tilley, C. E., The petrology of the granitic mass of Cape Willoughby, Kangaroo 

Island, pt. 1: Roy. Soc. South Australia Trans. and Proc., vol. 43, pp. 328-338, 1919. 

Bro:wne, W. R., The igneous rocks of Encounter Bay: Roy. Soc. South Australia 

Trans. and Proc., vol. 44, pp. 1-57, 1920. 

u Bowen, N. L., Diabase and aplite of the Cobalt silver area: Canadian Min: 

Inst. Jour., vol. 12, pp. 523-527, 1909. Collins, W. H., Gowganda mining division. 

Canada Geol. Survey Mem. 33, pp. 64-68, 1913. 

15 Falconer, J. D., The igneous geology of the Bathgate and Linlithgow Hills: 

Roy. Sol(. Edinburgh Trans., vol. 45, pp. 147-148, 1908. 

16 Holmquist, P. J ., Om Rodoomradets rapakivi och gangbergarter: Sveriges geol. 

Undersokning, ser. C, No .. l81, pp. 83-84, 1899. 

17 Hate\}, F. H., ·on the occurrence of soda felsites (keratophyres) in County 

Wicklow, Ireland: Geol. Mag., dec. 3, vol. 6, pp. 7o-73, 1889. 

1d'bom!ls, H. H., and Jones, 0. T ., op. cit., pp. 38o-381. 

19 Flett, J. S., The geology of Knapdale, Jura, and North Kintyre: Scotland 

G.eol. Stri:vey Mem. 28, pp. 93-95, 1911. 

20 Clough, C. T., The geological structure of the northwest Highlands of Scotland: Great Britain Geol. Survey Mem. p. 32, 1907. 

21 Htigbom, IVar, Petrografiska studier Vid Nybergsfaltet: Geol. Foren. Forb., 

vol. 42, p. 174, 1920. 

22 L~itakari, A., Einige Albitepidotgesteine von Siid Finland: Corum. geol. 

Finlande Bull., vol. 9, No. 51, 1918.' Makinen, Eero, op. cit., pp. 145-146. 

.23 Butler, B. S., Pyrogenetic epidote: Am. Jour. Sci., 4th ser., vol. 28, pp. 27-32, 

1909. 

2' Watson, T. L., op. cit., p. 77. 

25 Horwood, C. B., and Wade, A., op. cit., p. 549. 

26 Grubenmann, U., Beitragezur Geologiedes·Unterengadines, Teil2, Die KristalJinen Gesteine: Beitrage geol. Karte Schweiz, Neue Folge, Lief. 23, p. 194, 1909. 

21 Baskow, Gunnar, SOdra Storfj!l.llet im siidlichen Lappland, eine petrographische 'und geologische Studie im zentralen Teil des skandinavischen Hochgebhies: Sveriges geol. Understlkning Arsbok 21, No.5, ser. C, No. 350, pp. 137-

179, 192!~ ' 

28 Hinterlechner K., and Von John, op. cit., p. 135. 

29 Flett; J. 8., op. cit. (1911), p. 93. 

30 Phillips~ F. C., op. cit., p. 74. 

mineral in the albite-quartz porphyrite 31 of Victoria. 

Evidences of particular richness in water have been 

noted in many of the rocks; in fact, nearly every 

description of highly albitic and siliceous intrusive 

rocks that the writer has been able to find contains 

mention of a notably high content of water in the 

parent magma. This feature is also noted by Daly, 32 

although he emphasizes resurgent rather than juvenile 

water as the agent. 

Evidences of replacement or features suggesting 

some replacement also seem to be especially common 

among these rocks. Bragger describes albite rims 

about microperthite crystals in · a soda granite from 

Norway,33 and their occurrence is suggestive of replacement though not convincing. Sollas's description of · 

granophyre veins in gabbro with nests or "miarolitic 

cavities" in the gabbro filled by quartz and feldspar 

crystals '~ of larger dimensions than the feeding dikelets" certainly suggests replacement. 34 The grano:-

phyre, though albitic, carries . principally potash 

feldspar. 

According to Harker,35 the highly albitic Carrock 

Fell granophyre corrodes the gabbro in contact with 

it. Some of the features mentioned by Harker are 

suggestive of replacement, although it is probable that 

such phenomena are not on a very large ~cale. Phillips 36 has regarded some but not all of the albite in 

his riebeckite-bearing Shetland dike as of replacement 

ongm. Some of the quartz-feldspar relations in the 

very siliceous border facies of the Eskdale granite 

described by Dwerryhouse 37 are highly suggestive of 

replacement. The feldspar involved is, however, oligoclase rather than albite. Most of the highly sodic 

· microgranites described by De Lapparent 38 sho:w replacement phenomena, so interpreted by him, with, 

however, the belief that the replacements were magmatic and occurred prior to the consolidation of the 

rock. The evidence he advances to fix the time of 

the replacements does not seem to the present writer 

at all convincing, as it is based chiefly on the idea that 

fractured feldspars would not normally retain their 

angular shapes during replacement, and hence that 

broken albite fe.ldspars are of pre.brecciation origin. 

31 Howitt, A. W., op. cit., pp. 43; 46. 

32 Daly, R. A., Igneous rocks and their origin, pp. 243, 339-340, 437, New York, 

1914. 

33 Brogger, W. C., Die Eruptivgesteine des Kristianiagebietes: I, Die GroruditTinguait Serie: Vidensk. Skrifter, I, Mat.-Naturv. Klasse, 1894, No.4, pp. 127, 128. 

at Sollas, W. J., On the volcanic district of Carlingford and Slieve Gullion, pt. 1, 

On the relation of the granite to the gabbro of Barnavave, Carlingford: Roy. Irish 

Acad. Trans., vol. 30, pp. 477-512, 1894. 

as Harker, A., Carrock Fell-a study in the variation of igneous rock masses, pt. 2, 

The C8.rrock Fell granophyre: Geol. Soc. London Quart. Jour., vol. 51, pp. 135-137, 

1895. 

36 Phillips, F. C., op. cit., p. 74. 

37 Dwerryhouse, A. R .. On some intrusive rocks in the neighborhood of Eskdale, 

Cumberland: Geol. Soc. London Quart. Jour., vol. 65, p. 63, pl. 3, fig. 2, p. 65, 1909. 

a8 De Lapparent, J ., op. cit., pp. 243, 244, 246, 248, 269. 
.. '~ 

' ... 

REPLACEMENT ORIGIN OF ALBITE GRANITE NEAR SPARTA, OREG. 81 

"Poikilitic" quartz in feldspars of the albite granite 

of the Riesengebirge may well be of replacement ori-

. gin.39 Some of the quartz in the segregation veins 

in the quartz diabase described by Falconer 40 is regarded by him as secondary. The albite of the Orange 

Grove granite is regarded by Horwood and Wade 41 

as having replaced oligoclase. · Geijer has described 

albite granite selvages along potash granite contacts 

which · he regards as perhaps due to albitizationY 

Descriptions in the literature are commonly somewhat 

obscure, and other albite granites may possess replacement features. It is probable that sorrie . do not, 

however. 

Other noteworthy features of albite granites and 

albitites include the common presence of quartz 43 of a 

notably milky color, due perhaps, as in the Swedish 

examples cited on page 74, to rutile inclusions, and 

the still more common occurrence· of graphic or micro- . 

graphic texture. The enun1eration of all the occurrences of graphic textures in these rocks would include 

well over half of all to which the writer has found 

reference. 

Another noteworthy feature of these albite-rich 

rocks is their common association with crushing phenomena. Cataclastic features have been mentioned 

by Horwood and Wade/4 Elsden,45 Grubenmann, 46 

Hinterlechner and Von John/7 and Tliomas.48 

39 Milch, L., op. cit., pp. 177- 178. 

40 Falconer, J. D., op. cit., p. 149. 

. 41 Horwood, C. B., and Wade, A., op. cit., p. 550. 

42 Geijer, Per, Geology of the iron-ore fields at Masugnsbyn: Sveriges geol. Under80kning Arsbok 22, No. 1, ser. C, No. 51, pp. 37-38, 1928. 

43 Jaquet, J. B., Geology of the Broken Hill lode and Barrier Ranges mining field: 

New South Wales Geol. Survey Mem., Geology No.5, pp. 50-53, 1894. Milch, L., 

op. cit. (1899), p. 184. Tilley, C. E ., op. cit. (1919), p. 329. 

HHorwood, C. B., and Wade, A., op. cit., p. 550. 

46 Elsden, J. V., On the St. David's Rock series: Geol. Soc. London Quwt. Jour., 

vol. 64, ·p. 27fr277, 1908. 

46 Grubenmann, U.,Beitr!i.gezur Geologie des Unterengadines, Teil2, Die Kristallinen Gesteine: Beitr. geol. Karte Schweiz, Neue Folge, Lief. 23, pp. 191-192, 1909. 

47 Hinterlechner, K., and Von John, C., op. cit., pp. 134-138. 

48 Thomas, H. H., op. cit., p. 325 and others. 

0 

CONCLUSION 

It has been o~n that many albite granites elsewhere arel char~l cteri. zed by features found i~ ~he Sparta . ro ks. hese include common assoCiatiOn 

with crushfi.ng p enom(ma, widespread occurrence of 

graphic te ture , of epidot.e and other low:temperature and pydrqUs mafic mmerals, and of milky and 

rutilated quartz, 11and unusual ~mounts of repl~cement. 

Although there is a temptatiOn to generalize from 

. these feat res nd conclude that albite granites in . 

general originat, d through the replaceme~t. processes 

to which the W(riter has referred the ong1n .of ~he 

Sparta rocks, it fs probable th~t such a gen~~alizat~on would be J nsouf d· The findings of the wnter with 

respect to the S1arta rocks ar,e in agreem.ent with the 

thesis of ~o:ve 9 t~at albite! granites are of hydro-. 

thermal origin, rut It does not appear that a survey 

of the worlf· liter ture on such. r ocks is at ~II conclusive 

on the mat er. tit seems that !albite granites may well 

originate in diffJrent ways. Indeed, as Knopf 50 has 

pointed out, thk occurrence of highly siliceous and 

soda-rich yolca4ic ~l~sses i~ ;ery su.ggestive that 

liquids of the compositiOn of albite granite can be and 

are produ9ed hi magmatic differentiation. Though 

the present stud~ seems to supt ort Bowen's conclusion, 

the wri~er feels ith.at it is to~ arly to assert that the 

conclusiOn [has tiversal vahdlity. · . . . 

. I I 

I CKNOWLEDGMENTS 

The pai:rl!.stakihg criticism of the manuscript and 

helpful dis ussio s of the problem by T. B. Nolan 

and C. S. Ross,fLf the United States Geological Survey, are frate lly acknowledged. Many of the 

photomicrographls were taken by M. · N. Short, of the 

Geological ~urve . 

49 Bowen, N. :cl.,'The eyolution of the igneous rock~, p. 132, ~rince~on, 192~. w Knopf, Adolph, revier of Bowen, N. L., EvolutiOn of the Igneous rocks. Am. 

Jour. Sci., 5th seri' vol. 17,,p. 380, 1929.