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Cristobalite

Big Photo

Caspar quarry, Ettringer Bellerberg Mt. (Bellberg Mt.; Bellenberg Mt.; Billenberg Mt.; Boilenberg Mt.), Bellerberg volcano, Ettringen, Mayen, Eifel Mts, Rhineland-Palatinate, Germany
© Fred Kruijen

Show Cristobalite Photos (49)
Formula:
SiO
 
2
System:TetragonalColour:Blue grey, brown, grey, ...
Lustre:VitreousHardness:6 - 7
Name:Named after its locality (Cerro San Cristobal, Mexico)


Post-volcanic, magmatic, and secondary.

Classification of Cristobalite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:4/D.01-30
Nickel-Strunz 10th (pending) edition ID:4.DA.15

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
A : With small cations: Silica family
Dana 8th edition ID:75.1.1.1

75 : TECTOSILICATES Si Tetrahedral Frameworks
1 : Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Hey's CIM Ref.:7.8.5

7 : Oxides and Hydroxides
8 : Oxides of Si
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Type Occurrence of Cristobalite

Type Locality:Cerro San Cristóbal, Mun. de Pachuca, Hidalgo, Mexico
Year of Discovery:1887

Occurrences of Cristobalite

Geological Setting:In vesicles and lithophysae

Physical Properties of Cristobalite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:Blue grey, brown, grey, yellow, or white
Streak:White
Hardness (Mohs):6 - 7
Tenacity:Brittle
Density (measured):2.32 - 2.36 g/cm3
Density (calculated):2.33 g/cm3

Crystallography of Cristobalite

Crystal System:Tetragonal
Class (H-M):4 2 2 - Trapezohedral
Space Group:P41 21 2
Cell Parameters:a = 4.9709(1) Å, c = 6.9278(2) Å
Ratio:a:c = 1 : 1.394
Unit Cell Volume:V 171.18 ų (Calculated from Unit Cell)
Z:4
Morphology:Pseudo octahedral crystals, commonly dendritic, spherulites.
Twinning:On {111}
Crystal Atlas:
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Cristobalite no.1 - Goldschmidt (1913-1926)

About Crystal Atlas

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The mindat.org Crystal Atlas allows you to view a selection of crystal drawings of real and idealised crystal forms for this mineral and, in certain cases, 3d rotating crystal objects. You need Java to see these. You can download Java for free - click here to download Java

The 3d models and java code are kindly provided by www.smorf.nl. You can control the movement of the models by holding down the left mouse-button over the 3d model and moving your mouse. Keyboard controls are:

: default positions
t/T: decrease/increase transparency x/X: next/previous texture
b/B: next/previous background w: toggle wireframe
s: toggle sticks m: toggle miller indices
k: toggle crystallographic axes =/-: zoom in/out
r: stop/start rotation 1/2/3
X-Ray Powder Diffraction:
d-spacingIntensity
4.05 (100)
3.135 (11)
2.841 (13)
2.485 (20)
2.465 (5)
2.118 (5)
Comments:For synthetic material.

Optical Data of Cristobalite

Type:Uniaxial (-)
RI values: nω = 1.487 nε = 1.484
Maximum Birefringence:δ = 0.003

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate

Chemical Properties of Cristobalite

Formula:
SiO
 
2
Essential elements:O, Si
All elements listed in formula:O, Si
Common Impurities:Fe,Ca,Al,K,Na,Ti,Mn,Mg,P

Relationship of Cristobalite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
4.DA.05Quartz
SiO
 
2
4.DA.10Opal
SiO
 
2
·nH
 
2
O
4.DA.10Tridymite
SiO
 
2
4.DA.20Mogánite
SiO
 
2
4.DA.25Melanophlogite
46SiO
 
2
·6(N
 
2
,CO
 
2
)·2(CH
 
4
,N
 
2
)
4.DA.30Lechatelierite
SiO
 
2
4.DA.35Coesite
SiO
 
2
4.DA.40Stishovite
SiO
 
2
4.DA.45Keatite
4.DA.50Seifertite
SiO
 
2
Related Minerals - Hey's Index Grouping:

- +
7.8.1Quartz
SiO
 
2
7.8.2Coesite
SiO
 
2
7.8.3Tridymite
SiO
 
2
7.8.4Stishovite
SiO
 
2
7.8.6Lechatelierite
SiO
 
2
7.8.7Silhydrite
3SiO
 
2
·H
 
2
O
7.8.8Opal
SiO
 
2
·nH
 
2
O
7.8.9Mogánite
SiO
 
2

Other Names for Cristobalite

Synonyms:
α-Cristobaliteb-CristobaliteLow CristobaliteLussatine
Other Languages:
Dutch:Cristobaliet
Estonian:Kristobaliit
French:Cristobalite
German:Cristobalit
α-Cristobalit
b-Cristobalit
Cristobalitchalcedon
Lussatit
Tiefcristobalit
Italian:Cristobalite
Japanese:クリストバライト
Polish:Krystobalit
Portuguese:Cristobalita
Romanian:Cristobalit
Russian:Кристобалит
Spanish:α-Cristobalita
b-Cristobalita
Cristobalita
Lussatita
Ukrainian:Кристобаліт

Other Information

Thermal Behaviour:Inverts from high cristobalite at 268C.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Cristobalite

Reference List:Murdoch, Joseph (1942), Crystallographic notes, cristobalite, stephanite, natrolite: Am. Min.: 27: 500-506.

Henderson, J.H., M.L. Jackson, J.K. Syers, R.N. Clayton & R.W. Rex (1971), Cristobalite Authigenic origin in relation to montmorillonite and quartz origin in bentonite: Clays and Clay Minerals: 19: 229-238.

Murata, K.J. & J.K. Nakata (1974), Cristobalite stage in the diagenesis of diatomaceous shale: Science: 184: 567-568.

Richet, P., Bottinga, Y., Deniélou, L., Petitet, J.P., and Téqui, C. (1982) Thermodynamic properties of quartz, cristobalite, and amorphous SiO2: drop calorimetry measurements between 1000 and 1800 K and a review from 0 to 2000 K. Geochimica et Cosmochmica Acta: 46: 2639-2658.

Internet Links for Cristobalite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Cristobalite in the Natural History Museum (London) online catalogue
  • Cristobalite details from Handbook of Mineralogy (PDF)
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    Localities for Cristobalite

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    Copyright © Jolyon Ralph and Ida Chau 1993-2009. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register. Current server date and time: 8th Oct 2009 09:10:57