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.

Type Locality:

ⓘ Northwest Africa 1934 meteorite (NWA 1934), Northwest Africa Meteorites

Dimorph of:

Dmitryivanovite

Low-pressure CaAl₂O₄ dimorph.

Compare brownmillerite, grossite, hibonite, and addibischoffite.

Unique IdentifiersHide

Mindat ID:

40468

Long-form identifier:

mindat:1:1:40468:2

Similar NamesHide

Groatite	A valid IMA mineral species	NaCaMn₂(PO₄)[PO₃(OH)]₂
Groutite	A valid IMA mineral species - grandfathered	Mn³⁺O(OH)
Korteite	A synonym of Koenenite
Krautite	A valid IMA mineral species	Mn(HAsO₄) · H₂O
Kruťaite	A valid IMA mineral species	CuSe₂
Kuratite	A valid IMA mineral species	Ca₂(Fe₅²⁺Ti)O₂[Si₄Al₂O₁₈]

IMA Classification of KrotiteHide

IMA status:

Approved

Approval year:

2010

First published:

2011

Classification of KrotiteHide

Strunz-mindat (2026):

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

Mineral SymbolsHide

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
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 KrotiteHide

Lustre:

Vitreous

Transparency:

Transparent

Colour:

Colorless

Streak:

White

Hardness:

6½ on Mohs scale

Tenacity:

Brittle

Cleavage:

Distinct/Good
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 KrotiteHide

Type:

Biaxial (-)

RI values:

n_α = 1.608(2) n_β = 1.629(2) n_γ = 1.635(2)

2V:

Measured: 54.4° (5), Calculated: 55.6°

Max. Birefringence:

δ = 0.027
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.

Thickness: 30 µm Order divisions

Rotation:

Surface Relief:

High (positive)
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.

Focus:

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.

Thickness: 30 µm

Stage rotation: 0°

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 KrotiteHide

Mindat Formula:

CaAl₂O₄

Element Weights:

Element	% weight
O	40.495 %
Al	34.146 %
Ca	25.360 %

Calculated from ideal end-member formula.

Elements listed:

Al, Ca, O - search for minerals with similar chemistry

Crystallography of KrotiteHide

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)°

Ratio:

a:b:c = 1.074 : 1 : 1.879

Unit Cell V:

1,072.21 Å³ (Calculated from Unit Cell)

Morphology:

No crystal forms observed in type material.

Twinning:

None observed.

Comment:

Space group P21/n.

Crystal StructureHide

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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4

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CIF File Best | x | y | z | a | b | c

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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

data_global
_chemical_name_mineral 'Krotite'
loop_
_publ_author_name
'Kahlenberg V'
_journal_name_full 'European Journal of Mineralogy'
_journal_volume 13 
_journal_year 2001
_journal_page_first 403
_journal_page_last 410
_publ_section_title
;
 On the Al/Fe substitution in iron doped monocalcium
 aluminate - the crystal structure of CaAl1.8Fe0.2O4
;
_database_code_amcsd 0006865
_chemical_compound_source 'Synthetic'
_chemical_formula_sum 'Ca (Al1.817 Fe.183) O4'
_cell_length_a 8.758
_cell_length_b 8.112
_cell_length_c 15.311
_cell_angle_alpha 90
_cell_angle_beta 90.21
_cell_angle_gamma 90
_cell_volume 1087.761
_exptl_crystal_density_diffrn      2.992
_symmetry_space_group_name_H-M 'P 1 21/n 1'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '1/2+x,1/2-y,1/2+z'
  '1/2-x,1/2+y,1/2-z'
  '-x,-y,-z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_U_iso_or_equiv
Ca1   0.24010   0.03520   0.08910   1.00000   0.01130
Ca2   0.26810   0.46970   0.07160   1.00000   0.01370
Ca3   0.73960   0.52820   0.24700   1.00000   0.01870
AlT1   0.42360   0.32700   0.23840   0.92600   0.00780
FeT1   0.42360   0.32700   0.23840   0.07400   0.00780
AlT2   0.41970   0.72610   0.23320   0.90400   0.00840
FeT2   0.41970   0.72610   0.23320   0.09600   0.00840
AlT3   0.59830   0.82900   0.07810   0.89800   0.00760
FeT3   0.59830   0.82900   0.07810   0.10200   0.00760
AlT4   0.61200   0.22220   0.08090   0.91100   0.00900
FeT4   0.61200   0.22220   0.08090   0.08900   0.00900
AlT5   0.93580   0.72940   0.09150   0.88700   0.00750
FeT5   0.93580   0.72940   0.09150   0.11300   0.00750
AlT6   0.93880   0.33440   0.09220   0.92400   0.00830
FeT6   0.93880   0.33440   0.09220   0.07600   0.00830
O1   0.07750   0.23960   0.02400   1.00000   0.01210
O2   0.01770   0.53120   0.11140   1.00000   0.01690
O3   0.05500   0.86670   0.14870   1.00000   0.01610
O4   0.24760   0.24470   0.20250   1.00000   0.01410
O5   0.43390   0.25880   0.02740   1.00000   0.01390
O6   0.43050   0.85550   0.14060   1.00000   0.01550
O7   0.43410   0.52490   0.18780   1.00000   0.01820
O8   0.58470   0.22700   0.19580   1.00000   0.01680
O9   0.67950   0.02340   0.05420   1.00000   0.01680
O10   0.75520   0.35980   0.04650   1.00000   0.01690
O11   0.74620   0.72760   0.13490   1.00000   0.01580
O12   0.91930   0.24650   0.19720   1.00000   0.01540
loop_
_atom_site_aniso_label
_atom_site_aniso_U_11
_atom_site_aniso_U_22
_atom_site_aniso_U_33
_atom_site_aniso_U_12
_atom_site_aniso_U_13
_atom_site_aniso_U_23
Ca1 0.01200 0.00930 0.01280 0.00060 0.00420 0.00150
Ca2 0.01220 0.01340 0.01550 0.00190 -0.00110 0.00120
Ca3 0.01680 0.01830 0.02120 0.00030 0.00030 -0.00100
AlT1 0.00790 0.00880 0.00670 -0.00130 0.00020 -0.00050
FeT1 0.00790 0.00880 0.00670 -0.00130 0.00020 -0.00050
AlT2 0.00680 0.01110 0.00750 0.00060 0.00160 0.00060
FeT2 0.00680 0.01110 0.00750 0.00060 0.00160 0.00060
AlT3 0.00770 0.00800 0.00730 0.00150 0.00130 0.00010
FeT3 0.00770 0.00800 0.00730 0.00150 0.00130 0.00010
AlT4 0.00700 0.01260 0.00770 -0.00080 0.00140 -0.00100
FeT4 0.00700 0.01260 0.00770 -0.00080 0.00140 -0.00100
AlT5 0.00570 0.01070 0.00610 0.00070 0.00090 0.00020
FeT5 0.00570 0.01070 0.00610 0.00070 0.00090 0.00020
AlT6 0.00770 0.00860 0.00880 0.00100 0.00150 0.00060
FeT6 0.00770 0.00860 0.00880 0.00100 0.00150 0.00060
O1 0.01250 0.01310 0.01090 0.00200 0.00420 0.00170
O2 0.01860 0.01410 0.01810 -0.00060 -0.00220 0.00040
O3 0.01760 0.01730 0.01360 -0.00490 0.00080 -0.00010
O4 0.01020 0.01650 0.01560 0.00110 0.00130 -0.00010
O5 0.01260 0.01490 0.01430 0.00280 0.00110 -0.00230
O6 0.01600 0.01650 0.01540 0.00340 0.00330 0.00410
O7 0.02390 0.01590 0.01480 -0.00080 0.00140 -0.00020
O8 0.01340 0.02560 0.01120 0.00580 0.00300 0.00130
O9 0.01500 0.01400 0.02140 0.00080 0.00680 -0.00140
O10 0.01880 0.01260 0.01940 -0.00130 0.00190 0.00300
O11 0.01310 0.02090 0.01360 0.00220 0.00150 0.00300
O12 0.01160 0.02380 0.01080 -0.00040 -0.00100 0.00360

X-Ray Powder DiffractionHide

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 EnvironmentHide

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 KrotiteHide

Type Locality:

ⓘ Northwest Africa 1934 meteorite (NWA 1934), Northwest Africa Meteorites

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).

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:

Chlormayenite	Diopside	Gehlenite	Grossite	Hercynite
Hexamolybdenum	Hibonite	Perovskite	Spinel

Synonyms of KrotiteHide

IMA2010-038

Other Language Names for KrotiteHide

Dutch:Krotiet

German:Krotit

Common AssociatesHide

Associations 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 Hide

4.BC.	Abelloemringerite	Cu₂Pb₂Mn³⁺Mn⁴⁺ ₃O₁₁(OH)(H₂O)₂ · H₂O	Orth. mmm(2/m2/m2/m) : Imma
4.BC.	Ellinaite	CaCr₂O₄	Orth. mmm(2/m2/m2/m) : Pnma
4.BC.	Addibischoffite	Ca₂Al₆Al₆O₂₀	Tric. 1 : P1
4.BC.5	Karlleuite	Ca₂MnO₄	Tet. 4/mmm(4/m2/m2/m) : I4/mmm
4.BC.05	Marokite	CaMn³⁺₂O₄	Orth.
4.BC.10	Dmitryivanovite	CaAl₂O₄	Mon. 2/m : P2₁/b
4.BC.15	Warkite	Ca₂Sc₆Al₆O₂₀	Tric. 1 : P1
4.BC.25	Kudryavtsevaite	Na₃(Mg,Fe)(Fe,Ti)₂Ti₃O₁₂	Orth. mmm(2/m2/m2/m) : Pbcm
4.BC.30	Tululite	Ca₁₄(Fe³⁺,Al)(Al,Zn,Fe³⁺,Si,P,Mn,Mg)₁₅O₃₆	Iso. 23 : F23
4.BC.30	Valleyite	Ca₄Fe₆O₁₃	Iso. 43m : I43m
4.BC.40	Bacaferrite	BaCaFe₄O₈	Trig. 3m(32/m) : P31m

Fluorescence of KrotiteHide

In UV light:

Not fluorescent.

Other InformationHide

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 KrotiteHide

mindat.org URL:

https://www.mindat.org/min-40468.html
Please feel free to link to this page.

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External Links:

Look for Krotite on Webmineral

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Look for Krotite on Mineralien Atlas

Raman and XRD data at RRUFF project

References and PDF downloads at RRUFF project

American Mineralogist Crystal Structure Database

Handbook of Mineralogy page PDF

Mineral Dealers:

Buy from D. Joyce minerals

References for KrotiteHide

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

Ma, C., Kampf, A. R., Connolly, H. C., Beckett, J. R., Rossman, G. R., Smith, S. A. S., Schrader, D. L. (2011) Krotite, CaAl2O4, a new refractory mineral from the NWA 1934 meteorite. American Mineralogist, 96 (5) 709-715 doi:10.2138/am.2011.3693

(2021) Krotite. Handbook of Mineralogy. Mineralogical Society of America

Localities for KrotiteHide

Showing 3 localities.

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the

symbol to view information about a locality. The

symbol next to localities in the list can be used to jump to that position on the map.

Hide all sections | Show all sections

Locality ListHide

- 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.


Israel
Haifa District Kishon river Kishon Mid Reach zone 2 ⓘ Mount Carmel	Ma et al. (2023)
ⓘ Rakefet magmatic complex	doi.org (n.d.) +1 other reference

Northwest Africa Meteorites (TL)
ⓘ Northwest Africa 1934 meteorite (NWA 1934) (TL)	Williams et al. (2010) +1 other reference

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Krotite

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