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MINERALOGY:W.LINDGREN

249

Amer. J. Math.} 37, 1915 (29).
Schottky, Acta Math., 27, 1903 (235).
6 Coble, Amer. J. Math., 41, 1919 (243).
7 Wirtinger, Math. Ann., 27, 1892 (261); Untersuchung ilber Thetafunetioners,
Leipzig (1895).
8Coble, Amer. J. Math., 32, 1910 (333).
9 Shenton, Ibid., 372 1915 (247).
10 Cf. Coble, t. c., p. 352.
4 Conner,

5MELANOVANADITE, A NEW MINERAL FROMMIN A RAGRA, PASCO, PERU
By W ALDEMAR LINDGREN
DEPARTMEN'f OF MINING, METALLURGY AND GEOLOGY, MASSACHUSETTS INSTITUTE
OF TECHNOLOGY

Communicated, March 9, 1921

Late in 1920 Mr. 'W. Spencer Hutchinson, Consulting Engineer for theVanadium Company of America, brought to my attention three specimensof a m~neral collected by him at Mina Ragra, Peru. He suspected that it
was a new mineral, and (pis opinion was proved correct by chemical andoptical examination. The formula is 2CaO. 3V20 5 .2V20 4 and I wish to propose for it the name of Melanovanadite, in allusion to it being practicallythe only vanadium mineral of a deep black color. 1The mineral occurs in acicular bunches on black brecciated shale, theindividual crystals being at most 3 mm. long.
The greater thickness of the needles is about 0.5 mm. ranging down to0.1 and 0.01 mm. The color is black, luster almost submetallic, streakvery dark reddish bxown. The hardness is 2.5 the specific gravity 3.477
at 15 0 C. t-fhe habit of the crystals is prismatic, parallel to c, with monoclinic symmetry. The principal faces consist of a flat, striated prism,
the longer diagonal being parallel to the b axis, minor pinacoidal faces, andusually well developed terminal faces of pyramid's and smaller domes.
The crystals have a perfect cleavage parallel to (010).
Under the microscope the crystals remain black except in very thInprisms which are translucent with brown color.
Flat cleavage pieces parallel to the clinopinacoid only become translucent when the thickness is about 0.003 mm. and then show maximum extinction of about 15 0. Resting on the prism t100) the crystals becomebrown translucent with a thickness of about 0.03 mm. and then show lower
extinctions of 12° to 13°, while these resting more nearly on the orthopinacoid extinguish at lower angles. The perfect cleavage being perpen1 The ending Hvanadite" is an obsolete form of "vanadinite," but there can scarcely
be any objection to using this form in the present case.

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MINERALOGY: W. LINDGREN

PRoe. N. A. S.

dicular to the poorly developed orthopinacoid, extinctions of 0 0 are rarely
seen. Exact optical measurements are difficult on account of the deepcolor. Obscure hyperbolae show on the prism faces and it is probablethat the plane of the optic axes lies parallel to the perfect cleavage (010).
The absorptiqn is very strong. 1"'he a ray is visible with dark yellowish
brown color through the prism faces and the 9rthopinacoid and has according to a determination kindly made by Professor C. H. Warren acoefficient of refraction of 1.74; while the ~ and 'Y rays are somewhat
higher but cannot be measured exactly on account of the strong absorption~ The {3 and 'Y rays therefore lie in the 010 plane of perfect cleavage
and their absorption is so strong that such cleavage pieces only become
translucent in extremely thin plates, with dark reddish brown color, {3and 'Y differing slightly in depth of tint. The double refraction is strong.
The material was analysed by Professor L. F. Hamilton of the Massachusetts Institute of Technology, who reported the following composition:
V205
V204
CaO
MgO
A120sFe20a
Silica

52.61
33.34
9.89
.27
1.89
1.66
99.66

Assuming the alumina, iron oxide, magnesium and silica to be
impurities from the admixed shale the analysis may be recalculated to:
V20s

V204
CaO

54.90
34.78
10.32
100.00From this we calculate
V20s

54.90
182

V20 4

3~~8 = 0.2090.302

CaO

10.32 = 0.184
56
V2 0 S : V204 : CaO = 302 : 209 : 184or approximately 3: 2: 2. The formula would therefore:be,2 CaO.3V20 5.2V204
The calculated composition of this would be:
V20s
V204
CaO

55.16
33.54
11.30
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MINERALOGY:W.LINDGREN

251

Before the blowpipe the mineral fuses very easily to a brown liquid but
gives no flame reaction for calcium. It gives strong bead reactions forvanadium. It is easily soluble, with apple green color, in HNO g, HCI,
and dilute H 2SOa. Upon the evaporation the solution gives a red or brown
residue. In potassium hydroxide melanovanadite is easily soluble withbrownish color.
Editorial Note :-1-\his issue of the PROCEEDINGS, those immediately preceding, and those immediately to follow, have been seriously delayed by
the nation-wide printers' strike which began on May first, 1921.
l--\he Editors and the publisher of the PROCEEDINGS desire to express
their gratitude to the authors and to the subscribers for the patience
which has been shown in respect to these trying delays and to assure
them that all efforts are being made by all concerned toward getting thePROCEEDINGS back to regular and .prompt publication with every indication that success will be assured in the very near future.
In such an emergency the printing of reprints has to be given second
place as compared with the publication of the PROCEEDINGS but ,ve hope
to ship all reprints ordered without undue delay.
In order to facilitate the issuance of delayed numbers it has been necessary to make up the various articles in some cases in an order materiallydifferent from that of their receipt.
'