Gatumbaite Mineral Data
General Gatumbaite Information
Chemical Formula:
CaAl2(PO4)2(OH)2•(H2O)
Composition:
Molecular Weight = 336.01 gm
Calcium 11.93 % Ca 16.69 % CaO
Aluminum 16.06 % Al 30.34 % Al2 O3
Phosphorus 18.44 % P 42.24 % P2 O5
Hydrogen 1.20 % H 10.72 % H2 O
Oxygen 52.38 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
CaAl2 (PO4 )2 (OH)2 •(H2 O)
IMA Status:
Approved IMA 1977
Locality:
Buranga pegmatite, near Gatumba, Gisenyi Province, Rwanda. Link to MinDat.org Location Data.
Name Origin:
Named for the locality.
Name Pronunciation:
Gatumbaite + Pronunciation
Gatumbaite Image
Images:
Images:
Gatumbaite Crystallography
Axial Ratios:
a:b:c =1.3556:1:2.1126
Cell Dimensions:
a = 6.907, b = 5.095, c = 10.764, Z = 2; beta = 91.05° V = 378.73 Den(Calc)= 2.95
Crystal System:
Monoclinic Space Group: P12/m,P 2,Pm
X Ray Diffraction:
By Intensity(I/Io ): 2.241(1), 4.21(1), 1.726(0.75),
Physical Properties of Gatumbaite
Cleavage:
{???} Good, {???} Good
Color:
White.
Density:
2.92
Diaphaneity:
Translucent
Fracture:
Brittle - Splintery - Brittle fracture leaving splintery fragments.
Habit:
Rosette - Bundled tabular aggregates resembling rose flower petals.
Habit:
Scaly - Morphology like fish scales.
Habit:
Wheat Sheaf - Bundle shaped aggregates resembling wheat sheafs after hand reaping wheat.
Hardness:
4-5 - Fluorite-Apatite
Luminescence:
Non-fluorescent.
Luster:
Pearly
Streak:
white
Optical Properties of Gatumbaite
Gladstone-Dale:
CI meas = -0.014 (Superior) - where the CI = (1-KPDmeas /KC ) CI calc = -0.003 (Superior) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.2123,KPDmeas = 0.2145,KC = 0.2116 Ncalc = 1.62
Optical Data:
Biaxial (-), a=1.61, b=1.63, g=1.639, bire=0.0290, 2V(Calc)=66, 2V(Meas)=65.
Calculated Properties of Gatumbaite
Electron Density:
Bulk Density (Electron Density)=2.95 gm/cc note: Specific Gravity of Gatumbaite =2.95 gm/cc.
Fermion Index:
Fermion Index = 0.0004142297 Boson Index = 0.9995857703
Photoelectric:
PEGatumbaite = 2.83 barns/electronU=PEGatumbaite x r Electron Density= 8.35 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Gatumbaite is Not Radioactive
Gatumbaite Classification
Dana Class:
42.11.12.01 (42) Hydrated Phosphates, etc., Containing Hydroxyl or Halogen
(42.11) where (AB)4 (XO4)3 Zq � x(H2O)
(42.11.12) Gatumbaite Group
42.11.12.01 Gatumbaite CaAl2(PO4)2(OH)2•(H2O) P12/m,P 2,Pm Mono
42.11.12.02 Kleemanite ZnAl2(PO4)2(OH)2•3(H2O) P 2, P 21 , P 2/m or P 21 /m Mono
Strunz Class:
08.DJ.10 08 - PHOSPHATES, ARSENATES, VANADATES
08.D - Phosphates, etc
08.DJ -With large and medium-sized cations, (OH, etc.):RO4 = 1:l
08.DJ.10 Gatumbaite CaAl2(PO4)2(OH)2•(H2O) P12/m,P 2,Pm Mono
Other Gatumbaite Information
References:
NAME( Dana8) PHYS. PROP.(Dana8) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
See Also:
Links to other databases for Gatumbaite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
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Gatumbaite
CaAl2(PO4)2(OH)2•(H2O)
Dana No: 42.11.12.01 Strunz No: 08.DJ.10
Locality:
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