Mineralogy Database

Prehnite Mineral Data

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General Prehnite Information

Help on Chemical  Formula: Chemical Formula: Ca2Al2Si3O10(OH)2
Help on Composition: Composition: Molecular Weight = 395.38 gm
   Calcium   20.27 %  Ca   28.37 % CaO
   Aluminum  13.65 %  Al   25.79 % Al2O3
   Silicon   21.31 %  Si   45.59 % SiO2
   Hydrogen   0.25 %  H     2.28 % H2O
   Oxygen    44.51 %  O
            ______        ______ 
            100.00 %      102.02 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Ca2Al2Si3O10(OH)
Help on Environment: Environment: Hydrothermally altered rocks.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1789
Help on Locality: Locality: Haslach, Harzburg and Oberstein, Germany. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named after the Dutch Colonel, H. Von Prehn (1733-1785).
Help on Name Pronunciation: Name Pronunciation: Prehnite Say PREHNITE
Help on Synonym: Synonym: ICSD 69402
  PDF 29-290

Prehnite Image

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Comments: Very lustrous and brilliant prehnite.
Location: Deep Sahara, Morocco: Djbel Melh, Bou-Arfa. Scale: 9 x 6.5 cm.
© Fabre Minerals

Prehnite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.8427:1:3.3784
Help on Cell Dimensions: Cell Dimensions: a = 4.61, b = 5.47, c = 18.48, Z = 2; V = 466.00 Den(Calc)= 2.82
Help on Crystal System: Crystal System: Orthorhombic - Pyramidal H-M Symbol (mm2) Space Group: P 2cm
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.55(1), 3.08(1), 3.48(0.9),
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 1) ( 1 1 0) ( 1 0 0) ( 0 0 1)

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Physical Properties of Prehnite

Help on Cleavage: Cleavage: {001} Distinct
Help on Color: Color: Colorless, Gray, Yellow, Yellow green, White.
Help on Density: Density: 2.8 - 2.95, Average = 2.87
Help on Diaphaneity: Diaphaneity: Subtransparent to translucent
Help on Fracture: Fracture: Brittle - Generally displayed by glasses and most non-metallic minerals.
Help on Habit: Habit: Globular - Spherical, or nearly so, rounded forms (e.g. wavellite).
Help on Habit: Habit: Reniform - "Kidney like" in shape (e.g.. hematite).
Help on Habit: Habit: Stalactitic - Shaped like pendant columns as stalactites or stalagmites (e.g. calcite).
Help on Hardness: Hardness: 6-6.5 - Orthoclase-Pyrite
Help on Luminescence: Luminescence: Fluorescent, Short UV=blue white mild peach, Long UV=yellow.
Help on Luster: Luster: Vitreous - Pearly
Help on Streak: Streak: colorless

Optical Properties of Prehnite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.025 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.045 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2252,KPDmeas= 0.2209,KC= 0.2155
Ncalc = 1.6 - 1.64
Help on Optical Data: Optical Data: Biaxial (+), a=1.61-1.637, b=1.615-1.647, g=1.632-1.67, bire=0.0220-0.0330, 2V(Calc)=58-68, 2V(Meas)=64-70. Dispersion weak, r > v.
Help on Pleochroism (x): Pleochroism (x): colorless.
Help on Pleochroism (y): Pleochroism (y): colorless.

Calculated Properties of Prehnite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.86 gm/cc
note: Specific Gravity of Prehnite =2.88 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PEPrehnite = 3.70 barns/electron
U=PEPrehnite x rElectron Density= 10.60 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Prehnite is Not Radioactive

Prehnite Classification

Help on  Dana Class: Dana Class: (72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
  (72.01)with 4-membered rings
  (72.01.03)Dana Group Prehnite Ca2Al2Si3O10(OH)2 P 2cm mm2
Help on  Strunz Class: Strunz Class: 09.DP.20 09 - SILICATES (Germanates)
  09.D - Inosilicates* Structural terminology according to Liebau (1985)
  09.DP -Transitional ino-phyllosilicate structures
09.DP.20 Prehnite Ca2Al2Si3O10(OH)2 P 2cm mm2

Other Prehnite Information

Help on See Also: See Also: Links to other databases for Prehnite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Amethyst Galleries' Mineral Gallery
5 - Athena
6 - EUROmin Project
7 - Ecole des Mines de Paris
8 - Franklin Minerals(Dunn)
9 - Franklin Minerals(Palache)
10 - GeoScienceWorld
11 - Google Images
12 - Google Scholar
13 - Handbook of Mineralogy (MinSocAm)
14 - Handbook of Mineralogy (UofA)
15 - MinDAT
16 - Mineralienatlas (Deutsch)
17 - Minerals in Thin Sections-Humboldt State
18 - Online Mineral Museum
19 - QUT Mineral Atlas
20 - Ruff.Info
21 - Scandinavian mineral gallery
22 - Tradeshop.com - The Rainbow of Gems
23 - UCLA - Petrography Thin-Sections
25 - theimage

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Dana No: Strunz No: 09.DP.20





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