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Krotite (Krotit)

Collectors Summary

Color farblos
Streak color weiß
Lustre Glasglanz
Hardness (Mohs) 6.5~
Cleavages gut (100) und (010)
Fracture muschelig
Crystal System monoklin, P21/n

Additional information / Summary

Eines der ältesten Minerale im Sonnensystem

Chemism

Chemical formula

CaAl2O4

Chemical composition

Aluminium, Calcium, Sauerstoff

Unit weight: 158.0391964 u; Number of atoms in the formula: 7

Info

Empirical formula:

CaAl2O4

Element

Symbol

Weight%

Atoms

Atoms%

Atom weight (u)

Sum weight (u)

Oxygen

O

40.49

4

57.14

15.9994300

63.9977200

Aluminium

Al

34.15

2

28.57

26.9815382

53.9630764

Calcium

Ca

25.36

1

14.29

40.0784000

40.0784000

Analysis wt%

Al2O3 : 63.50, CaO : 35.73 (Ref: American Mineralogist 2011)

Strunz 9th edition incl. updates

4.BB.

4: Oxide, Hydroxide (Oxide, Hydroxide, V[5,6]-Vanadate, Arsenite, Antimonite, Bismutite, Sulfite, Selenite, Tellurite, Iodate)
B: Metall: Sauerstoff = 3:4 und vergleichbare
B: Mit ausschließlich mittelgroßen [Kationen]

Lapis Classification

IV/B.09-007

IV: OXIDE
B: Oxide mit Verhältnis Metall zu Sauerstoff = 3:4 (Spinelltyp M3O4 und verwandte Verbindungen)

Classification by Hölzel

4.CE.755

4: OXIDES
C: R2O3 Sesquioxides
E: Other complex Oxides, mostly hextrig
7: Brownmillerite-Group

IMA status

anerkannt CNMNC im Sept. 2010

Mineral status

anerkanntes Mineral

Optical Properties

Color

farblos

Streak color

weiß

Diaphaneity (Transparency)

transparent

Lustre

Glasglanz

max. Birefringence

0.027

Birefringence chart\! Krotite title=Birefringence chart Krotite

Michel-Levy Color Chart viewed according to the maximum birefringence (at 30μm). Mineral color is not taken into account. Click on the image to enlarge or change thickness.

RI value α / ω / n

1.608

RI value β

1.629

RI value γ / ε

1.635

Ri mean

1.624

2V angle

Biaxial (-) 54°

Crystallography

Crystal System

monoklin

Class (H-M)

2/m

Space Group number

14

Space Group

P21/n

Cell parameters a (Å)

8.700

Cell parameters b (Å)

8.099

Cell parameters c (Å)

15.217

Cell parameters a/b or c/a

1.074

Cell parameters c/b

1.879

Cell parameters α

90°

Cell parameters β

90.18

Cell parameters γ

90°

Z

12

Volume (ų)

1072.204

Crystal structure

Struktur ermittelt, Tridymit-Struktur, siehe C. Ma et al. (2011)

X-Ray Powder Diffraction

4.694(28), 2.977(100), 2.527(35), 2.410(40), 1.927(22), 1.583(23), 1.528(31), 1.459(33)

XRD chart Krotite

Calculated from d-spacing and intensity at 0.1541838 nm (Cu)

Crystal Structure 3D

Open larger view

Physical Properties

Hardness (Mohs)

6.5~

VHN (Hardness Vickers)

960 (ungefähre Angabe abgeleitet aus der Mohshärte)

Density (g/cm³)

2.94 ber.

2.937 ( ρ calc. Mineralienatlas )

Cleavages

gut (100) und (010)

Fracture

muschelig

Tenacity

spröde

(Co-)Type locality

(Co-)Type locality

Marokko/Drâa-Tafilalet, Region/Errachidia (Er-Rachidia), Provinz/Er-Rissani, Cercle/Rissani/NWA 1934 CV3 Kohlenstoffreicher Chondrit Meteorit

Type material

Natural History Museum of Los Angeles County, California, USA,

Collection number of type material

63275

Preface

Author (Name, Year)

C. Ma et al. (2011)

References

Chi Ma, Anthony R. Kampf, Harold C. Connolly, Jr., John R. Beckett, George R. Rossman, Stuart A. Sweeney Smith, Devin L. Schrader: Krotite, CaAl2O4, a new refractory mineral from the NWA 1934 meteorite. American Mineralogist 96 (2011) S.709-715.

Krotite, IMA 2010-038. CNMNC Newsletter, October 2010, page 901; Mineralogical Magazine, Vol. 74(5) (2010) S.899-902.

Hofmeister, A.M., Wopenka, B., Locock, A.J. (2004): Spectroscopy and structure of hibonite, grossite, and CaAl2O4: Implications for astronomical environments. Geochimica et Cosmochimica Acta, 68, 4485-4503.

Other languages

German

Krotit

English

Krotite

Simplified Chinese

始铝钙石

CNMNC (IMA)-Number

IMA 2010-038

CNMNC symbol

Symbol

Kro

Locations with GPS information

IDs

GUSID (Global unique identifier short form) hVpnzosYAEqKlMTaAO4e7g
GUID (Global unique identifier) CE675A85-188B-4A00-8A94-C4DA00EE1EEE
Database ID 6930