Mineralogy Database

Tridymite Mineral Data

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General Tridymite Information

Help on Chemical  Formula: Chemical Formula: SiO2
Help on Composition: Composition: Molecular Weight = 60.08 gm
   Silicon  46.74 %  Si  100.00 % SiO2
   Oxygen   53.26 %  O
           ______        ______ 
           100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: (SiO2)
Help on Environment: Environment: Cavities in volcanic rocks.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1868
Help on Locality: Locality: Occurs world wide. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: From the Greek Tridymos - "triplex."
Help on Name Pronunciation: Name Pronunciation: Tridymite + Pronunciation Say TRIDYMITE
 

Tridymite Image

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  Tridymite

Comments: Clear, pseudohexagonal crystals of tridymite on matrix.
Location: Bellerberg quarry, Laacher See, Rhineland-Palatinate, Germany. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Tridymite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.5769:1:4.7551
Help on Cell Dimensions: Cell Dimensions: a = 9.932, b = 17.216, c = 81.864, Z = 330; alpha = 90°, beta = 90°, gamma = 90° V = 13,997.87 Den(Calc)= 2.35
Help on Crystal System: Crystal System: Triclinic - Pedial H-M Symbol (1) Space Group: F1
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 4.107(1), 4.328(0.9), 3.818(0.5),
 

Physical Properties of Tridymite

Help on Cleavage: Cleavage: {0001} Indistinct, {1010} Imperfect
Help on Color: Color: Colorless, White, Yellowish white, Gray.
Help on Density: Density: 2.28 - 2.33, Average = 2.3
Help on Diaphaneity: Diaphaneity: Transparent to translucent
Help on Fracture: Fracture: Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.
Help on Habit: Habit: Platy - Sheet forms (e.g. micas).
Help on Habit: Habit: Spherical - Spherical, rounded aggregates.
Help on Hardness: Hardness: 6.5-7 - Pyrite-Quartz
Help on Luminescence: Luminescence: Fluorescent, Short UV=dark cherry red.
Help on Luster: Luster: Vitreous (Glassy)
Help on Magnetism: Magnetism: Nonmagnetic
Help on Streak: Streak: white
 

Optical Properties of Tridymite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.002 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.021 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2035,KPDmeas= 0.2075,KC= 0.208
Ncalc = 1.47 - 1.49
Help on Optical Data: Optical Data: Biaxial (+), a=1.471-1.482, b=1.472-1.483, g=1.474-1.488, bire=0.0030-0.0060, 2V(Calc)=50-72, 2V(Meas)=36-90. Dispersion none.
Help on Pleochroism (x): Pleochroism (x): colorless.
Help on Pleochroism (y): Pleochroism (y): colorless.
Help on Pleochroism (z): Pleochroism (z): colorless.
 

Calculated Properties of Tridymite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.30 gm/cc
note: Specific Gravity of Tridymite =2.31 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.02
Boson Index = 0.98
Help on Photoelectric: Photoelectric: PETridymite = 1.80 barns/electron
U=PETridymite x rElectron Density= 4.14 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Tridymite is Not Radioactive
 

Tridymite Classification

Help on  Dana Class: Dana Class: 75.01.02.01 (75)Tectosilicate Si Tetrahedral Frameworks
  (75.01)SiO2 with [4] coordinated Si
  (75.01.02)Dana Group
 
75.01.02.01 Tridymite SiO2 F1 1
Help on  Strunz Class: Strunz Class: 04.DA.10 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate
  04.D - Metal:Oxygen = 1:2 and similar
  04.DA -With small cations
 
04.DA.10 Opal SiO2•n(H2O) None
 
04.DA.10 Tridymite SiO2 F1 1
 

Other Tridymite Information

Help on References: References: NAME( Duda&Rejl90) PHYS. PROP.(Collectors Book of Fluorescent Minerals) OPTIC PROP.(Larousse des Mineraux,1981)
Help on See Also: See Also: Links to other databases for Tridymite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - GeoScienceWorld
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - MinDAT
10 - Mineral and Gemstone Kingdom
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Tridymite

SiO2
Dana No: 75.01.02.01 Strunz No: 04.DA.10
Locality:

 

Notes:

 

 
   
 


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