Krotite
A valid IMA mineral species
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About Krotite
Formula:
CaAl2O4
Colour:
Colorless
Lustre:
Vitreous
Hardness:
6½
Specific Gravity:
2.944 (Calculated)
Crystal System:
Monoclinic
Name:
Named for Alexander N. Krot (b. 1959), a cosmochemist at the University of Hawaii, in recognition of his significant contributions to the understanding of early solar system processes.
Dimorph of:
Unique Identifiers
Mindat ID:
40468
Long-form identifier:
mindat:1:1:40468:2
GUID
(UUID V4):
(UUID V4):
9b8871f5-47ce-40d2-af07-451ae875e04e
IMA Classification of Krotite
Classification of Krotite
4.BC.35
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
B : Metal: Oxygen = 3:4 and similar
C : With medium-sized and large cations
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
B : Metal: Oxygen = 3:4 and similar
C : With medium-sized and large cations
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 |
---|---|---|
Kro | 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 Krotite
Vitreous
Transparency:
Transparent
Colour:
Colorless
Streak:
White
Hardness:
6½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Good on {100} and {010}.
Good on {100} and {010}.
Fracture:
Conchoidal
Density:
2.944 g/cm3 (Calculated)
Comment:
Calculated values are 2.944 g/cm3 (empirical formula) and 2.937 g/cm3 (ideal formula). Could not bea measured due to lack of material.
Optical Data of Krotite
Type:
Biaxial (-)
RI values:
nα = 1.608(2) nβ = 1.629(2) nγ = 1.635(2)
2V:
Measured: 54.4° (5), Calculated: 55.6°
Max Birefringence:
δ = 0.027
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
None observed.
Optical Extinction:
X = b; Y ≈ a; Z ≈ c.
Pleochroism:
Weak
Comments:
Colorless to very pale gray.
Comments:
Absorption: X > Y = Z (barely noticeable).
Chemistry of Krotite
Mindat Formula:
CaAl2O4
Elements listed:
Crystallography of Krotite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 8.6996(3) Å, b = 8.0994(3) Å, c = 15.2170(11) Å
β = 90.188(6)°
β = 90.188(6)°
Ratio:
a:b:c = 1.074 : 1 : 1.879
Unit Cell V:
1,072.21 ų (Calculated from Unit Cell)
Morphology:
No crystal forms observed in type material.
Twinning:
None observed.
Comment:
Space group P21/n.
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
---|---|---|---|---|---|---|---|
0006865 | Krotite | Kahlenberg V (2001) On the Al/Fe substitution in iron doped monocalcium aluminate - the crystal structure of CaAl1.8Fe0.2O4 European Journal of Mineralogy 13 403-410 | 2001 | synthetic | 0 | 293 | |
0017810 | Krotite | Horkner W, Muller-Buschbaum H (1976) Zur kristallstruktur von CaAl2O4 Journal of Inorganic and Nuclear Chemistry 38 983-984 | 1976 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
4.694 Å | (28) |
2.977 Å | (100) |
2.527 Å | (35) |
2.410 Å | (40) |
1.927 Å | (22) |
1.583 Å | (23) |
1.528 Å | (31) |
1.459 Å | (33) |
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
Stage 1: Primary nebular phases | 4.567-4.561 |
3 : Solar nebular condensates (CAIs, AOAs, URIs) | >4.565 |
Stage 3a: Earth’s earliest Hadean crust | >4.50 |
7 : Ultramafic igneous rocks |
Type Occurrence of Krotite
General Appearance of Type Material:
Aggregates with the individual crystals ranging from 10 to 350 μm in size.
Place of Conservation of Type Material:
Type material consists of three thin sections (UA2169TS1, UA2169TS2, UA2169TS3).
National Museum of Natural History (Smithsonian Institution), Washington, D.C., USA, USNM 7590 (section UA2169TS1).
Co-type material:
Natural History Museum of Los Angeles County, California, USA, number 63275 (fragments from section UA2169TS2).
National Museum of Natural History (Smithsonian Institution), Washington, D.C., USA, USNM 7590 (section UA2169TS1).
Co-type material:
Natural History Museum of Los Angeles County, California, USA, number 63275 (fragments from section UA2169TS2).
Geological Setting of Type Material:
An unusual Ca-,Al-rich refractory inclusion in a carbonaceous chondrite meteorite. A low-pressure CaAl2O4 mineral, likely formed by condensation or crystallization from a melt in the solar nebula.
Associated Minerals at Type Locality:
Synonyms of Krotite
Common Associates
Associated Minerals Based on Photo Data:
1 photo of Krotite associated with Hexamolybdenum | (Mo,Ru,Fe,Ir,Os) |
1 photo of Krotite associated with Hercynite | Fe2+Al2O4 |
Related Minerals - Strunz-mindat Grouping
4.BC. | Addibischoffite | Ca2Al6Al6O20 |
4.BC. | Ellinaite | CaCr2O4 |
4.BC. | Igelströmite | Fe3+(SbPb)O4 |
4.BC.05 | Marokite | CaMn3+2O4 |
4.BC.10 | Dmitryivanovite | CaAl2O4 |
4.BC.15 | Warkite | Ca2Sc6Al6O20 |
4.BC.25 | Kudryavtsevaite | Na3(Mg,Fe)(Fe,Ti)2Ti3O12 |
4.BC.30 | Tululite | Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36 |
4.BC.30 | Valleyite | Ca4Fe6O13 |
Fluorescence of Krotite
Not fluorescent.
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 Krotite
mindat.org URL:
https://www.mindat.org/min-40468.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Krotite
Reference List:
Hörkner, W., Müller-Buschbaum, Hk. (1976) Zur kristallstruktur von CaAl2O4. Journal of Inorganic and Nuclear Chemistry, 38 (5) 983-984 doi:10.1016/0022-1902(76)80011-5
Kahlenberg, Volker (2001) On the Al/Fe substitution in iron doped monocalcium aluminate - the crystal structure of CaAl1.8Fe0.2O4. European Journal of Mineralogy, 13 (2) 403-410 doi:10.1127/0935-1221/01/0013-0403
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2010) New minerals and nomenclature modifications approved in 2010, CNMNC Newsletter No 5. Mineralogical Magazine, 74 (5) 859-862 doi:10.1180/s0026461x00056887
Localities for Krotite
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).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
Israel | |
| |
Northwest Africa Meteorites (TL) | |
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Northwest Africa 1934 meteorite, Northwest Africa Meteorites