MINERALOGICAL MAGAZINE, MARCH 1973, VOL. 39, PP. 6 9 ' - 7 3

Heyite and brackebuschite compared
R. F. SYMESBritish Museum (Natural History), Cromwell Road, London, S.W. 7
S. A. W I L L I A M S
Phelps Dodge Corporation, Douglas, Arizona
SUMMARY. Heyite (see preceding paper) is so strikingly similar to brackebuschite that a close comparison of the two species seemed advisable. Topotype brackebuschite (B.M. 55819) was used forthis purpose.
Brackebuschite is a vanadate of lead, manganese, and iron, heyite a vanadate of lead and iron.
Both species are monoclinic with diffraction symmetry P2, or P21/m.The X-ray cells are remarkably
close: a = 8"8io, 8"9IO; b = 6q55, 6"oi7; c = 7.65i , 7'734; fl = I I I ~ 3o', IIt~ 53' (brackebuschite
first). As might be expected, powder patterns are strikingly close as well.
Other than the similarities noted above, the minerals differ so fundamentally that they cannot be
the same--they are valid and distinct species. Optic orientations show c~: [ooi] 2o~ (in acute fl) for
brackebuschite, 36~ (in obtuse/3) for heyite. Indices are (brackebuschite first): ct 2'28, 2q85;/3 2"38,2"219; )' 2"49, 2"266 for the sodium D line.
Chemical differences are irreconcilable and reaffirm brackebuschite as Pb~(Mn,Fe,Zn)(VO4)2.H~O
while heyite is PbsFe~(VO4)~O4.
T HE striking similarities o f the qualitative chemistry a n d X - r a y d a t a o f b r a c k e b u s c h i t e
a n d heyite require some c o m m e n t if heyite is to be accepted as a new species w i t h o u t
reservation. Brackebuschite has h a d a long b u t tranquil history since first describedf r o m C o r d o b a , A r g e n t i n a ( R a m m e l s b e r g , I880). This remains the only u n d i s p u t e dlocality for brackebuschite, and later workers have never shown evidence o f confusionr e g a r d i n g the identity o f the mineral. Published d a t a for b r a c k e b u s c h i t e show g o o da g r e e m e n t a n d the mineral is well characterized.
F o r a c o m p l e t e c o m p a r i s o n o f heyite a n d b r a c k e b u s c h i t e it was necessary to determine some constants for brackebuschite t h a t h a d n o t previously been reported. W ealso p e r f o r m e d new chemical analyses. All new i n f o r m a t i o n was o b t a i n e d f r o m one
specimen in the British M u s e u m ( N a t u r a l History), B.M. 55819. This is a type locality
specimen p u r c h a s e d by the M u s e u m in I884, f r o m Mr. Hoseus, a n d it a p p e a r s to beo f superior quality to m a t e r i a l used by previous workers. I n this specimen brackebuschite occurs as well-terminated crystals f r o m o'4 to r- 5 m m in length in cavities
with cerussite, descloizite, and vanadinite. The gangue is a sheared granitic r o c k richin muscovite a n d showing replacement b y prismatic q u a r t z where it is m o s t severely
brecciated.

Morphology. T w o t e r m i n a t e d crystals were selected for measurement. The crystals
were o f similar h a b i t showing e l o n g a t i o n on [oIo] and m a r k e d flattening o n {IOO}.
9 Copyright the Mineralogical Society.

R. F. SYMES

70AND

S. A . W I L L I A M S

ONDeep striae on {IOO} are parallel to [OLO]. Both crystals showed a {IOO}, c ( o o I ) ,1 {~01}, k {~0I}. Forms found on only one crystal are d (IOi}, {i0I}, {~22},{02I}, and {~25} (?). A typical crystal is shown in fig. I. Crystals were carefully
examined for twinning but no twins were found; heyite commonly shows twinningon {II0}. No doubly terminated crystals could be found but crystals appear to be
attached to matrix by either + b or --b in roughly equal abundance.

m {IIO),

X-ray data. Powder patterns of heyite and brackebuschite are similar. Visualinspection however shows progressive deterioration of line matches and intensities
toward larger 20 values. Indexed patterns of the two species are compared in table I.
TABLE I. Powder patterns of heyite and brackebuschite, Cr-Ka radiation.

Intensities estimatedBrackebuschite
I483II893
IB-2-I0-5------

5B

2
I
61

Heyite

dmeas

dealt

hkl

I

dmeas

dcalc

hkl

8"I99
4"918
4'6o8
4"3o2
4"o9o
3"821
3"687
3'544
-3"413-3"244-3"O79-2'942--2"880
2"822
2"765
2'626

8'197
4"922
4"6o4
4"298
4"o99
3"815
3"687
3'559
3"524
3"4II
3'367
3"243
3"O95
3"O78
3'o8I
2'936
2"954
2"900
2"88I
2"825
2"765
2'623

lOO
IiO
ioi
2oi
200
IO~
Ill
oo2
21i
210
20~
II~
201
020
o12
3oT212lO2
I20
021
2IIII2289
5289
2
24I-3-I0
I
3-7-I
2-6
3

8.281
4"873
4"628
4"35o
4'134
3-861
3"674
3"592-3"412-3"248
3'II6
3"010
-2'97o-2"916
2'825-2"767
2.625

8"270
4'868
4'635
4"351
4'135
3'859
3"673
3'59o
3'5263"4O9
3"41I
3"249
3'117
3"011
3"082
2'97o
2"968
2"92o
2'829
2"774
2'768
2'628

IOO
IiO
loi
2oi
2oo
IO~iii
oo2
2IT
210
20~
lie
20I
020
oi2
3oi
2I~
lO2
120021
211
II2

X-ray cells of the two minerals are strikingly similar. Both minerals are monoclinicwith parameters:
Brackebuschite
Heyitea 8'8Io•
8"9Io•

b 6q55•
6'oi7•

c 7-65I•
7'734~o'oo4/3 i l i ~ 30'•
III~ 53'•

Barnes and Qurashi (I952) and Berry and Graham (I948) have given very similar datafor brackebuschite. Heyite occurs in doubly terminated crystals and shows no evidence
that it is not of class 2/m symmetry; its diffraction symmetry permits space groups
P21 or P21/m, and Pz~/m was chosen as more likely. Brackebuschite crystals have notHEYITE AND BRACKEBUSCHITE

7t

been found doubly terminated; morphological evidence given by crystals terminatedon = b and b suggests 2/m symmetry, and since diffraction symmetry permits spacegroups P21 or P21/m, P2a/m may be preferred as more likely. However, Fanfani andZanazzi (I967) have suggested P2L for brackebuschite as more likely on structuralgrounds.
rIoiilfy~0,0.

".. .:2o/[.
~176''....I/~/Q. ..-"....

IO ..

~..........0.0.

I ....

IIII[IF10s. I and 2: FIo. t (left). A typical brackebuschite crystal. FIG. 2 tright). Optic orientations ofbrackebuschite (left) and heyite (right).

Optics. Although refractive indices for brackebuschite have been reported previously(Larsen and Berman, I934), redetermination by the identical methods used for heyite
seemed desirable. Indices for both minerals were determined in S-Se melts for thesodium D line:
Brackebuschite
Heyitec~ 2 . z 8 + o . o i 5 ,2"I85--o'o1

fl 2'384-0"02,2"2t9:!:o-oi

y 2'49.-ko'oz
2.266~o.ot

Brackebuschite shows strong absorption in the melts for fl and ~,; heyite does not.
Both minerals have a large 2V; heyite is ( + ) 82 ~ to 89 ~ and brackebuschite is sensibly
9 ~176. The optic orientations of both minerals are presented in fig. 2, and one can see
the striking difference. For crystals lying on (IOO) brackebuschite gives an off-centred
optic axis figure and is length-slow with high birefringence. Heyite gives a well-centred
optic axis figure and is length slow but with very low birefringence in the sameorientation.

Chemistry. Grains were handpicked from a topotype brackebuschite specimen(B.M. 55819) and ultrasonically cleaned. During this process visible amounts of earthy
hematite were removed from innumerable tiny pits in the crystal surfaces. Several ofthese grains were mounted in an epoxy resin and polished. Twelve of these were thenanalysed qualitatively and checked for homogeneity before proceeding to quantitativeanalysis. In all the grains studied lead, zinc, manganese, vanadium, and iron weredetected, copper and phosphorus (reported by Rammelsberg and Doering) were sought
but not found (i.e. less than o'o5 %). The analyses for both heyite and brackebuschiteR. F. SYMES A N D S. A. W I L L I A M S ON

72

were m a d e using a C a m b r i d g e I n s t r u m e n t s G e o s c a n , with an accelerating voltage of
20 kV and a current of o ' 5 • Io -7 amps. Lead was determined using an analysed
anglesite s t a n d a r d from M o n t e p o n i , Sardinia; crocoite was used as a secondary
standard. Pure M n , Zn, V, and Fe metal s t a n d a r d s were used for the other elements
determined. The brackebuschite grains were analysed in the same run as repeat
analyses on the heyite grains. R a w d a t a for those elements determined were correctedusing the m e t h o d s described by S w e a t m a n and L o n g 0 9 6 9 ) and the M a s o n , Frost,a n d Reed (I969) microanalysis c o m p u t e r p r o g r a m m e . A t least ten p o i n t counts weret a k e n on each o f the grains (average largest dimension 250 microns).
TABLE I I .

Analyses of brackebuschite and (no. 8) heyite]

23

4

5

6

78

PbO
ZnO
FeO
MnO
V20~

6P90-520-20
9"526"562-1o'i 30"o4
9"660" 3069
2"76"325"261.o0"666.8
2"525' 5

62.6
0"93"o6-8
27'1

n.d.

n.d.

n.d.

n.d.

CuO
HzO

n.d.
.

n.d.

n.d.

.

n.d.
.

58'02
x"23
4'46
4"56
24'74
o'11
o'4I
2"43

76'3
0.80
8'2
n.d.
I2'7

P205

61"oo1-29
4"65
4"7725"32oq80"42
2-o3

n.d.
--

Total

98"62 *

97"67*

95'19'

96"46*

Ioo"4"

99"66

Io0"32"~98"o025"8
n.d.

n.d.
.

.

n.d.

* Totals not inclusive of H20 = 2.8 %.
n.d. Not detected.
t Including 3"o7 % insol, and 1.29 % Fe2Oa+Mn30~.
I, 2. Electron probe analyses; R. F. Symes. (Typical analyses of IO of the 12 grains studied.)3, 4. Electron probe analyses. (Analyses of the two grains with lower Mn-Fe ratios.)
5- Analysis by atomic absorption: C. J. EIliott (B.M.(N.H.)).
6. Rammelsberg (188o).
7. Doering (I883).
8. Averaged probe analyses of heyite grain, run concurrently with brackebuschite.
C o u n t s for Pb, Zn, V, and M n showed very little variation within each grain whereas
the counts for iron were variable in grains having a low Fe content.
Table II (cols. t and 2) shows the analyses o f two o f the brackebuschite grains, theanalyses being typical o f the results obtained on ten o f the grains selected, and withthe best surface polish. Only two o f the grains analysed showed any significant variation from these analyses; these analyses are shown in cols. 3 and 4 o f table II. T h e
principal differences are in the F e O / M n O ratio. The repeat heyite analyses duplicatedthose already presented in the previous paper. It is thought that the figures quoted arecorrect to __-" I o,o o f the a m o u n t present for the m a j o r elements.
7o9 m i c r o g r a m s o f the same cleaned sample were dissolved in HNO3, and Pb,Fe, Mn, Zn, Cu, and V were then determined by a t o m i c a b s o r p t i o n spectroscopy byc o m p a r i s o n with pure standard solutions. A Perkin Elmer 403 spectrometer was used
for the analyses. The analysis is shown in table 1I, col, 5 ; C u was again below detectionlevel.

HEYITE AND BRACKEBUSCHITE

x.734 mitligrammes were found to give 2.82 ~ H20 on heating to 550 ~temperatures (I ~o ~ and 44o ~ no water was released.

73

at lower

Conclusions. Our work on brackebuschite has essentially confirmed older resultswith but one exception: the formula should be rewritten as Pb2(Mn,Fe,Zn)(VO4)~.
H20. The ratio of Mn: Fe of I : I found by older analyses is undoubtedly fortuitousand probably represents the average ratio to be found in brackebuschite with someadmixed hematite. Heyite analyses done by the same method give the different anddistinct formula PbsFe2(VO4)204. The complicated coupled substitutions required torelate brackebuschite to heyite while demanding virtually no change in the X-ray cell
stretch credulity too far. The similarity o f the X-ray cells is better explained as mere
coincidence.
Acknowledgements. Peter G. Embrey gave advice freely during this study. F. B. Millett
assisted in cell refinement and indexing.

REFERENCESBARNES(W. n.) and QURASHI(M. M.), I952. Amer. Min. 37, 407-22.
BERRY(L. G.) and GRAHAM(A. R.), I948. Ibid. 33,489--95.
DOERING(A.), 1883. BoL Acad. Nac. Cienc., Cordoba, 5, 5oi-5.
FANFANI(L.) and ZANAZZI(P. F.), I967. Min. Mag. 36, 522-9 .

LARSEN(E.S.) and BERMAN(H.), I934. The microscopic determination of non-opaque minerals. U.S.
Geol. Surv. Bull. 848.

MASON(P. K.), FROST(M. T.), and REED (S. J. B.), I969. B.M.-I.C.-N.P.L. computer program forcalculating corrections in quantitative X-ray microanalysis. N.P.L. Report I.
RAMMELSBERG(K. F.), I880. Zeits. deutsch. Geol. GesetL 32, 7o8-I 3.
SWEATMAN(T. R.) and LONG(J. V. P.), I969. Journ. Petrology, 10, 332-76.
[Manuscript received 8 August z972]