Coesite Mineral Data

Coesite Mineral Data

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General Coesite Information

Chemical Formula:

SiO2

Composition:

Molecular Weight = 60.08 gm

Silicon 46.74 % Si 100.00 % SiO₂

Oxygen 53.26 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

(SiO₂)

Environment:

High temperature and high pressure polymorph of quartz (500-800 deg C, ~ 30-35 kbar). Formed in impact craters and ultra-high-pressure eclogite rocks.

IMA Status:

Valid Species (Pre-IMA) 1954

Locality:

Metor Crater, Cononino County, Arizona, USA. Link to MinDat.org Location Data.

Name Origin:

Named for Loring Coes, Jr. (1915-1973), American chemist, Norton Company, who first synthesized the phase.

Synonym:

ICSD 18112

PDF 14-654

Coesite Image

Images:

Coesite

Comments: Fine-grained, massive coesite.
Location: Meteor Crater, Canyon Diablo, Coconino County, Arizona, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Coesite

Comments: Coesite inclusion in garnet of eclogite sample (Eur. J. Mineral, 13:567).
Location: Ultra high-pressure metamorphic area of the Saidenbach reservoir, Erzgebirge, Germany, where micro-diamond-bearing gneiss occurs. Scale: Scale Bar 50 µm.
© Eur. J. Mineral

Coesite Crystallography

Axial Ratios:

a:b:c =0.5791:1:0.5791

Cell Dimensions:

a = 7.17, b = 12.38, c = 7.17, Z = 16; beta = 120° V = 551.18 Den(Calc)= 2.90

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/c

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 3.098(1), 3.432(0.5), 2.77(0.15),

Crystal Structure:

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Levien L , Prewitt C T , American Mineralogist , 66 (1981) p.324-333, High-pressure crystal structure and compressibility of coesite, P = 1 atm isotropic refinement

View Additional jPOWD Structure files for Coesite
[1] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [2] [20] [3] [4] [5] [6] [7] [8] [9]

Physical Properties of Coesite

Cleavage:

None

Color:

Colorless.

Density:

2.93

Diaphaniety:

Transparent

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Inclusions - Generally found as inclusions in other minerals.

Hardness:

7.5 - Garnet

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Coesite

Gladstone-Dale:

CI meas= 0.022 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.012 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2055,KPDmeas= 0.2034,KC= 0.208

Optical Data:

Biaxial (+), a=1.593-1.594, b=1.595, g=1.599, bire=0.0050-0.0060, 2V(Calc)=54-72, 2V(Meas)=54-64. Dispersion r < v weak.

Calculated Properties of Coesite

Electron Density:

r_electron=2.90 gm/cc
note: r_Coesite=2.90 gm/cc.

Fermion Index

Fermion Index = 0.02208
Boson Index = 0.97792

Photoelectric:

PE_Coesite= 1.80 barns/electron
U=PE_Coesite x r_electron= 5.20 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Coesite is Not Radioactive

Coesite Classification

Dana Class:

75.1.4.1 (75)Tectosilicate Si Tetrahedral Frameworks

(75.1)SiO2 with [4] coordinated Si

(75.1.4)Dana Group

75.1.4.1 Coesite SiO2 C 2/c 2/m

75.1.4.2 Moganite! SiO2 I2/a 2/m

Strunz Class:

IV/D.01-50 IV - Oxides

IV/D - Oxides with metal : oxygen = 1:2 (MO2 and related compounds)

IV/D.01 - Quartz group

IV/D.01-10 Quartz SiO2 P 3₁21,P 3₂21 3 2

IV/D.01-20 Tridymite SiO2 F1 1

IV/D.01-30 Cristobalite SiO2 P 4₁2₁2 4 2 2

IV/D.01-35 Moganite! SiO2 I2/a 2/m

IV/D.01-40 Melanophlogite SiO2·n(C,H,O,S) P 4₁/nbc 4/m 2/m 2/m

IV/D.01-40* Melanophlogite-beta! SiO2·n(C,H,O,S) P m3n 4/m 3 2/m

IV/D.01-50 Coesite SiO2 C 2/c 2/m

IV/D.01-60 Stishovite SiO2 P 4/mnm 4/m 2/m 2/m

IV/D.01-70 Lechatelierite* SiO2 None

IV/D.01-80 Opal SiO2·n(H2O) None

Other Coesite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Dana8)

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Print or Cut-and-Paste your Coesite Specimen Label here :

Coesite

SiO2
Dana No: 75.1.4.1 Strunz No: IV/D.01-50
Locality:

Notes: