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Glaucocerinite
A valid IMA mineral species - grandfathered
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About Glaucocerinite
Formula:
(Zn1-xAlx)(OH)2(SO4)x/2 · nH2O
(x < 0.5, n > 3x/2). May contain Cu replacing Zn (formula for type material is given as Zn13Al8Cu7(SO4)2O30.34H2O).
Colour:
Sky-blue, turquoise-blue, greenish, greyish, brownish
Lustre:
Waxy
Hardness:
1
Specific Gravity:
2.749
Crystal System:
Hexagonal
Member of:
Name:
From the Greek γλαυκός for "sky-blue" and κήρινος for "wax-like," in allusion to its colour and appearance.
Chemically similar to zincowoodwardite.
Compare also other members of the Woodwardite Group. Compare 'UM1985-07-OH:AlCuSZn' - corresponding to the alleged cotype specimen of glaucocerinite.
Compare also other members of the Woodwardite Group. Compare 'UM1985-07-OH:AlCuSZn' - corresponding to the alleged cotype specimen of glaucocerinite.
Unique Identifiers
Mindat ID:
1707
Long-form identifier:
mindat:1:1:1707:3
IMA Classification of Glaucocerinite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Zn2+1-xAlx(S6+O4)x/2(OH)2·nH2O (x<0.5, n>3x/2)
First published:
1932
Classification of Glaucocerinite
7.DD.35
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
D : With only medium-sized cations; sheets of edge-sharing octahedra
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
D : With only medium-sized cations; sheets of edge-sharing octahedra
31.4.8.1
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
4 : (AB)4(XO4)Zq·xH2O
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
4 : (AB)4(XO4)Zq·xH2O
25.5.10
25 : Sulphates
5 : Sulphates of Zn and Hg
25 : Sulphates
5 : Sulphates of Zn and Hg
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Gc | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Glaucocerinite
Waxy
Transparency:
Translucent
Colour:
Sky-blue, turquoise-blue, greenish, greyish, brownish
Comment:
Tints due to included impurities.
Hardness:
1 on Mohs scale
Density:
2.749 g/cm3 (Measured) 2.33 g/cm3 (Calculated)
Optical Data of Glaucocerinite
Type:
Biaxial (-)
RI values:
nα = 1.540(2) nβ = 1.554(2) nγ = 1.562(2)
2V:
Measured: 60° , Calculated: 72°
Birefringence:
High.
Max. Birefringence:
δ = 0.022
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Low (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
weak
Chemistry of Glaucocerinite
Mindat Formula:
(Zn1-xAlx)(OH)2(SO4)x/2 · nH2O
(x < 0.5, n > 3x/2). May contain Cu replacing Zn (formula for type material is given as Zn13Al8Cu7(SO4)2O30.34H2O).
(x < 0.5, n > 3x/2). May contain Cu replacing Zn (formula for type material is given as Zn13Al8Cu7(SO4)2O30.34H2O).
Crystallography of Glaucocerinite
Crystal System:
Hexagonal
Cell Parameters:
a = 3.070(8) Å, c = 32.65(1) Å
Ratio:
a:c = 1 : 10.635
Unit Cell V:
266.50 ų (Calculated from Unit Cell)
Morphology:
Occurs as masses with a radial-fibrous structure and concentric colour banding.
Comment:
Hexagonal (?). Point Group: n.d.; Space Group: n.d. ; Z = n.d
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.9 Å | (100) |
| 5.45 Å | (90) |
| 3.63 Å | (80) |
| 2.62 Å | (60) |
| 2.46 Å | (60) |
| 2.231 Å | (50) |
| 1.981 Å | (50) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47b : [Sulfates and sulfites] |
Type Occurrence of Glaucocerinite
General Appearance of Type Material:
Banded botryoidal crusts.
Place of Conservation of Type Material:
Dept. of Mineralogy and Crystallography, University of Vienna, Vienna, cat. no. C11.130; Natural History Museum, Vienna, Austria, cat. nos. G 1377, G 1378 (NOTE: the Handbook of mineralogy erroneously gives G 1378 and G 1379).
Hilarion Mine, Kamariza Mines, Agios Konstantinos, Lavreotiki, East Attica, Attica, Greece