Batagayite, CaZn2(Zn,Cu)6(PO4)4(PO3OH)3·12H2O, a new phosphate mineral from Këster tin deposit (Yakutia, Russia): occurrence and crystal structure
Batagayite, CaZn 2 (Zn,Cu) 6 (PO 4 ) 4 (PO 3 OH) 3 ·12H 2 O, is a new secondary phosphate mineral from the Këster deposit, Arga-Ynnykh-Khai massif, NE Yakutia, Russia. It is monoclinic, P 2 1 , a = 8.4264(4), b = 12.8309(6), c = 14.6928(9) Å, β = 98.514(6) o , V = 1571.05(15) Å 3 and Z = 2 (fr...
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| Published in: | Mineralogy and petrology Vol. 112; no. 4; pp. 591 - 601 |
|---|---|
| Main Authors: | , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Vienna
Springer Vienna
01-08-2018
Springer Nature B.V |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Batagayite, CaZn
2
(Zn,Cu)
6
(PO
4
)
4
(PO
3
OH)
3
·12H
2
O, is a new secondary phosphate mineral from the Këster deposit, Arga-Ynnykh-Khai massif, NE Yakutia, Russia. It is monoclinic,
P
2
1
,
a
= 8.4264(4),
b
= 12.8309(6),
c
= 14.6928(9) Å,
β
= 98.514(6)
o
,
V
= 1571.05(15) Å
3
and
Z
= 2 (from single-crystal X-ray diffraction data). Batagayite crystals are blades up to 2 mm long, flattened on {001} and elongated on [100]; blades often grow in radial aggregates. Associated minerals are arsenolite, native copper, epifanovite, fluorapatite, libethenite, Na-analogue of batagayite, pseudomalachite, quartz, sampleite, tobermorite, and Mg-analogue of hopeite. The streak is white and the luster is vitreous. The mineral is brittle and has a perfect cleavage on {001}, no parting was observed. The Mohs hardness is 3. Density, determined by the float-sink method in Clerici solution, is 2.90(3) g/cm
3
, and the calculated density is 3.02 g/cm
3
(using the empirical formula and single-crystal unit-cell parameters). Batagayite is biaxial, optically negative,
α
= 1.566 ± 0.002,
β
= 1.572 ± 0.002,
γ
= 1.573 ± 0.002 at 589 nm. 2
V
meas
. = 40(5)°, 2
V
calc
= 44.3°. Optical orientation:
Z
is perpendicular to (001), further details unclear. No dispersion or pleochroism were observed. The mean chemical composition determined by electron microprobe is: Na
2
O 0.31, MgO 1.39, Al
2
O
3
0.55, SiO
2
0.48, P
2
O
5
34.37, K
2
O 0.17, CaO 2.76, MnO 1.03, CuO 5.80, ZnO 35.62, CdO 0.24 wt%. The H
2
O content estimated from the crystal-structure refinement is 16.83 wt%, giving a total of 99.55 wt%. The empirical formula calculated on the basis of P + Si = 7 is (Zn
6.22
Cu
1.04
Ca
0.70
Mg
0.49
Mn
0.21
Al
0.15
Na
0.14
K
0.05
Cd
0.03
)
Σ9.03
(P
6.89
Si
0.11
)
Σ7.00
O
24.91
(OH)
3.09
·12.10H
2
O. The mineral easily dissolves in 10% room-temperature HCl. The eight diagnostic lines in the X-ray powder-diffraction pattern are (
I
-
d
[Å]-
hkl
): 100-14.59-001, 25-6.34-012, 11-6.02-111, 37-4.864-003, 13-4.766-112, 20-3.102-1
2
¯
4
¯
, 11-2.678-2
3
¯
3
¯
, 16-2.411-044. The crystal structure of batagayite was solved by direct methods and refined to
R
1
= 0.069 for 3847 independent reflections with
F
o
> 4σ(
F
o
). It is based upon complex heteropolyhedral [
M
8
(PO
4
)
4
(PO
3
OH)
3
(H
2
O)
9
]
2−
layers parallel to the (001) plane. The layer can be considered as consisting of three sublayers, one
A
and two
B
. The central
A
layer has the composition [
M
4
(PO
4
)
4
(H
2
O)
4
]
4−
and consists of the zigzag chains of edge-sharing (
M
O
6
) octahedra running parallel to the
a
axis and linked into layers by sharing peripheral O atoms. The (PO
4
) tetrahedra are attached above and below the holes created by the linkage of zigzag octahedral chains. The
B
sublayer consists of chains of (ZnO
4
) and (PO
3
OH) tetrahedra. The interlayer space is occupied by the Ca
2+
cations and H
2
O molecules. Batagayite is a secondary low-temperature mineral formed as a result of alteration of primary minerals such as native copper and fluorapatite. On the basis of its structural complexity calculated as 1058.257 bits/cell (taking into account contributions from H atoms), batagayite should be considered as a very complex mineral. The high complexity of batagayite is due to its high hydration state and the modular character of its structure, which contains both octahedral-tetrahedral layers and tetrahedral chains. |
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| ISSN: | 0930-0708 1438-1168 |
| DOI: | 10.1007/s00710-017-0551-x |