Gatumbaite
A valid IMA mineral species
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About Gatumbaite
Formula:
CaAl2(PO4)2(OH)2 · H2O
Colour:
White
Lustre:
Pearly
Hardness:
4 - 5
Specific Gravity:
2.92
Crystal System:
Monoclinic
Name:
Named for the type locality in the Gatumba District, Rwanda.
This page provides mineralogical data about Gatumbaite.
Unique Identifiers
Mindat ID:
1659
Long-form identifier:
mindat:1:1:1659:5
IMA Classification of Gatumbaite
Classification of Gatumbaite
8.DJ.10
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
J : With large and medium-sized cations, (OH, etc.):RO4 = 1:1
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
J : With large and medium-sized cations, (OH, etc.):RO4 = 1:1
42.11.12.1
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
11 : (AB)3(XO4)2Zq·xH2O
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
11 : (AB)3(XO4)2Zq·xH2O
19.8.15
19 : Phosphates
8 : Phosphates of Al and other metals
19 : Phosphates
8 : Phosphates of Al and other metals
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 |
|---|---|---|
| Gtb | 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 Gatumbaite
Pearly
Transparency:
Translucent
Colour:
White
Streak:
White
Hardness:
4 - 5 on Mohs scale
Tenacity:
Brittle
Fracture:
Splintery
Density:
2.92 g/cm3 (Measured) 2.95 g/cm3 (Calculated)
Optical Data of Gatumbaite
Type:
Biaxial (-)
RI values:
nα = 1.61 nβ = 1.63 nγ = 1.639
2V:
Measured: 65° , Calculated: 67°
Max. Birefringence:
δ = 0.029
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:
Moderate
Dispersion:
relatively strong
Optical Extinction:
Z = b; OAP ⊥ {010}.
Chemistry of Gatumbaite
Mindat Formula:
CaAl2(PO4)2(OH)2 · H2O
Element Weights:
Chemical Analysis
Oxide wt%:
| 1 | |
|---|---|
| P2O5 | 41,35 % |
| Al2O3 | 28,09 % |
| Fe2O3 | 2,20 % |
| MnO | 0,30 % |
| CaO | 17,35 % |
| Na2O | 0,30 % |
| H2O+ | 10,68 % |
| H2O- | 0,32 % |
| Total: | 98 % |
Crystallography of Gatumbaite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P2/m
Cell Parameters:
a = 6.907 Å, b = 5.095 Å, c = 10.764 Å
β = 91.05°
β = 91.05°
Ratio:
a:b:c = 1.356 : 1 : 2.113
Unit Cell V:
378.73 ų (Calculated from Unit Cell)
Z:
2
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.210 Å | (100) |
| 2.241 Å | (100) |
| 1.726 Å | (75) |
| 2.772 Å | (70) |
| 2.301 Å | (65) |
| 3.207 Å | (50) |
| 3.159 Å | (50) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 22 : Hydration and low-? subsurface aqueous alteration (see also #23) | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Geological Setting:
Andesite altered hydrothermally through hydrogen metasomatism (Mt. Perry, Australia).
Type Occurrence of Gatumbaite
General Appearance of Type Material:
White millimetric sheaves and rosettes.
Place of Conservation of Type Material:
Royal Museum of Central Africa, Tervuren, Belgium.
National Museum of Natural History, Washington, DC, USA.
National Museum of Natural History, Washington, DC, USA.
Geological Setting of Type Material:
Phosphate assemblage in a complex granite pegmatite.
Associated Minerals at Type Locality:
Synonyms of Gatumbaite
Other Language Names for Gatumbaite
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 8.DJ.05 | Johnwalkite | K(Mn2+,Fe2+,Fe3+)2(Nb5+,Ta5+)(PO4)2O2 · 2(H2O,OH) |
| 8.DJ.05 | Olmsteadite | KFe2+2(Nb5+,Ta5+)(PO4)2O2 · 2H2O |
| 8.DJ.15 | Camgasite | CaMg(AsO4)(OH) · 5H2O |
| 8.DJ.20 | Meurigite-K | KFe3+8(PO4)6(OH)7 · 6.5H2O |
| 8.DJ.20 | Phosphofibrite | (H2O,K)3.5Fe8(PO4)6(OH)7 · 5H2O |
| 8.DJ.20 | Meurigite-Na | NaFe3+8(PO4)6(OH)7 · 6.5H2O |
| 8.DJ.25 | Jungite | Ca2Zn4Fe3+8(PO4)9(OH)9 · 16H2O |
| 8.DJ.30 | Wycheproofite | NaAlZr(PO4)2(OH) · H2O |
| 8.DJ.35 | Ercitite | Na2Mn3+2(PO4)2(OH)2 · 4H2O |
| 8.DJ.40 | Mrázekite | Bi2Cu3(PO4)2O2(OH)2 · H2O |
| 8.DJ.45 | Attikaite | Ca3Cu2Al2(AsO4)4(OH)4 · 2H2O |
| 8.DJ.50 | Mengeite | Ba(Mg,Mn2+)Mn3+4(PO4)4(OH)4 · 4H2O |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Gatumbaite
mindat.org URL:
https://www.mindat.org/min-1659.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Gatumbaite
Reference List:
Fleischer, Michael; Pabst, Adolf, White, John Sampson (1978) New mineral names. American Mineralogist, 63 (7-8). 793-796
Localities for Gatumbaite
Showing 8 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Australia | |
| Duggan et al. (1990) |
| Duggan et al. (1990) | |
Czech Republic | |
| Breiter K. |
Japan | |
| Matsubara et al. (1998) |
Rwanda (TL) | |
| von Knorring (1972) +3 other references |
Sweden | |
| Ek et al. (1990) +1 other reference |
| Collection of NHM |
USA | |
| Segeler et al. (1981) +2 other references |
Quick NavTopAbout GatumbaiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Chemical AnalysisCrystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Buranga pegmatite, Muhororo, Ngororero District, Western Province, Rwanda