Mineralogy Database

Gypsum Mineral Data

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General Gypsum Information

Help on Chemical  Formula: Chemical Formula: CaSO4•2(H2O)
Help on Composition: Composition: Molecular Weight = 172.17 gm
   Calcium   23.28 %  Ca   32.57 % CaO
   Hydrogen   2.34 %  H    20.93 % H2O
   Sulfur    18.62 %  S    46.50 % SO3
   Oxygen    55.76 %  O
            ______        ______ 
            100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Ca(SO4)•2(H2O)
Help on Environment: Environment: Sedimentary evaporite deposits.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) Prehistoric
Help on Locality: Locality: Numerous localities worldwide. Naica, Chihuahua, Mexico. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: From the Greek, gyps meaning "burned" mineral. Selenite from the Greek in allusion to its pearly luster (moon light) on cleavage fragments.
Help on Name Pronunciation: Name Pronunciation: Gypsum Say GYPSUM
Help on Synonym: Synonym: Alabaster
  ICSD 2057
  PDF 33-311
  Satin Spar

Gypsum Image

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Comments: Bladed rosettes of gypsum.
Location: unknown. Scale: Specimen size 6 cm.
© Dave Barthelmy

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Comments: Pencil-sized acicular crystals of gypsum.
Location: Naica, Chihuahua, S.A., Mexico. Scale: Specimen size 5 cm.
© Dave Barthelmy

Gypsum Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.3741:1:0.4143
Help on Cell Dimensions: Cell Dimensions: a = 5.68, b = 15.18, c = 6.29, Z = 4; beta = 113.833° V = 496.09 Den(Calc)= 2.31
Help on Crystal System: Crystal System: Monoclinic - Prismatic H-M Symbol (2/m) Space Group: A2/a
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 7.63(1), 4.28(1), 3.07(0.8),2.87(0.5), 2.69(0.4), 2.09(0.3), 2.22(0.2), 3.8(0.2),
Help on Forms: Forms:

Dbl Clk - Start-Stop Rotation
RMB - Cycle Display Modes
Drag1 - Manipulate Crystal
Drag2 - Resize

S - Stereo
I - Indicies
<space> - Start-Stop Rotation
F - Fit to Screen
M - Menu

Help on Above

Forms: ( 0 1 0) ( 1 1 1) ( 1 2 0)

Warning: this java applet does not work in some browsers because of security restrictions.


Physical Properties of Gypsum

Help on Cleavage: Cleavage: {010} Perfect, {100} Distinct, {011} Distinct
Help on Color: Color: White, Colorless, Yellowish white, Greenish white, Brown.
Help on Density: Density: 2.3
Help on Diaphaneity: Diaphaneity: Transparent to translucent
Help on Fracture: Fracture: Fibrous - Thin, elongated fractures produced by crystal forms or intersecting cleavages (e.g. asbestos).
Help on Habit: Habit: Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
Help on Habit: Habit: Massive - Fibrous - Distinctly fibrous fine-grained forms.
Help on Habit: Habit: Tabular - Form dimensions are thin in one direction.
Help on Hardness: Hardness: 2 - Gypsum
Help on Luminescence: Luminescence: Fluorescent and phosphorescent, Short UV=orange yellow, Long UV=orange yellow.
Help on Luster: Luster: Pearly
Help on Streak: Streak: white

Optical Properties of Gypsum

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.027 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.022 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2268,KPDmeas= 0.2278,KC= 0.2219
Ncalc = 1.51
Help on Optical Data: Optical Data: Biaxial (+), a=1.519-1.521, b=1.522-1.523, g=1.529-1.53, bire=0.0090-0.0100, 2V(Calc)=58-68, 2V(Meas)=58. Dispersion strong, r > v.
Help on Pleochroism (x): Pleochroism (x): colorless.
Help on Pleochroism (y): Pleochroism (y): colorless.

Calculated Properties of Gypsum

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.36 gm/cc
note: Specific Gravity of Gypsum =2.31 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0019822214
Boson Index = 0.9980177786
Help on Photoelectric: Photoelectric: PEGypsum = 3.97 barns/electron
U=PEGypsum x rElectron Density= 9.37 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Gypsum is Not Radioactive

Gypsum Classification

Help on  Dana Class: Dana Class: (29)Hydrated Acid and Sulfates
  (29.06)where A XO4 � x(H2O)
  (29.06.03)Dana Group Gypsum CaSO4•2(H2O) A2/a 2/m
Help on  Strunz Class: Strunz Class: 07.CD.40 07 - SULFATES (SELENATES, TELLURATES)
  07.C - Sulfates (selenates, etc.) without Additional Anions, with H2O
  07.CD -With only large cations
07.CD.40 Gypsum CaSO4•2(H2O) A2/a 2/m

Other Gypsum Information

Help on See Also: See Also: Links to other databases for Gypsum :
1 - Alkali-Nuts(English)
2 - Am. Min. Crystal Structure Database
3 - Amethyst Galleries' Mineral Gallery
4 - Athena
5 - Franklin Minerals(Dunn)
6 - Franklin Minerals(Palache)
7 - GeoScienceWorld
8 - Glendale Community College
9 - Google Images
10 - Google Scholar
11 - Handbook of Mineralogy (MinSocAm)
12 - Handbook of Mineralogy (UofA)
13 - HyperPhysics
14 - MinDAT
15 - Mineral and Gemstone Kingdom
16 - Mineral of the Month
17 - Mineralienatlas (Deutsch)
18 - NSDL Reciprocal Net (JAVA)
19 - Online Mineral Museum
20 - Philatelic Mineralogy
21 - QUT Mineral Atlas
22 - Ruff.Info
23 - Scandinavian mineral gallery
24 - U.S. Fish & Wildlife Service
25 - University of Colorado - Mineral Structure Data
27 - YupRocks

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Dana No: Strunz No: 07.CD.40





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