General Information
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 Chemical Formula: |
KNa2Li(Fe++,Mn)2Ti2Si8O24 |
| Composition: |
Molecular Weight = 907.69 gm) |
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| Empirical Formula: |
KNa2LiFe2+1.5Mn2+0.5Ti2Si8O24 |
| Locality: |
Benitoite mine, San Benito, Co., California, USA. |
| Synonym: |
Carlosite |
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Neptunite Image
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Images: |
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Jet-black square prisms of Neptunite etched out of the enclosing white natrolite with minor benitoite. Beniotoite Gem Mine. San Benito Co. California, USA. 6.5 x 6 cm.
Photo by Francesc Fabre / Fabre Minerals |
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Classification
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| Dana Class: |
70.4.1.1 (70)Inosilicate Column or Tube Structures |
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(70.4)with linked chains forming cages |
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(70.4.1)Neptunite group |
| Strunz Class: |
VIII/F.37-10 VIII - Silicates |
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VIII/F - Inosilicates (chain and band) complex chain structure. Cylindric chains and others |
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VIII/F.37 - Neptunite series |
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Crystallography
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| Axial Ratios: |
a:b:c =1.3167:1:0.8008 |
| Cell Dimensions: |
a = 16.46, b = 12.5, c = 10.01, Z = 8; beta = 115.4ø V = 1,860.47 Den(Calc)= 6.48 |
| Crystal System: |
Monoclinic - Domatic H-M Symbol (m) Space Group: Cc |
| Forms: |
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Forms:
[0 0 1]
[1 0 0]
[0 -1 0]
[-1 -1 1]
[1 1 0]
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| X Ray Diffraction: |
By Intensity(I/Io): 3.186(1) 9.6(0.6) 3.517(0.45) |
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Physical Properties
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| Cleavage: |
[110] Good |
| Color: |
black or red. |
| Density: |
3.23 |
| Diaphaniety: |
Translucent |
| Habits: |
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Tabular - Form dimensions are thin in one direction., Crystalline - Coarse - Occurs as well-formed coarse sized cry stals. |
| Hardness: |
5-6 - Between Apatite and Orthoclase |
| Luminescence: |
Non-fluorescent. |
| Luster: |
Vitreous (Glassy) |
| Streak: |
brown |
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Optical Properties
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| Optical Data: |
Biaxial (+), a=1.69-1.6908, b=1.6927-1.7, g=1.7194-1.736, bire=0.0294-0.0452, 2V(Calc)=36-56, 2V(Meas)=36-49. Dispersion relatively strong. |
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Other Information
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| References: |
NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990) |
| See Also: |
Links to other databases for Neptunite :
1 -Alkali Nuts
2 -Athena Mineralogy
3 - EUROmin Project
4 -MinDat.org Location Data
5 -MinMax
6 -The Mineral Gallery
7 -WWW-MINCRYST
8 -theimage
9 -École des Mines de Paris
Search for Neptunite using:
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[All-The-Web]
[EXCITE]
[GO.COM]
[GOOGLE]
[Ixquick]
[LYCOS]
[LookSmart]
[MAMMA]
[MSN.COM]
[NORTHERN LIGHT]
[YAHOO]
Visit our Advertisers for Neptunite :
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Ask about Neptunite here :
Mindat.org's Discussion Groups
Mindat.org's Collecting Discussion Group
Mindat.org's General Discussion Group
Mindat.org's Swap Shop Discussion Group
Bob's Rockshop Rock Net Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Ask-A-Mineralogist from the Mineralogical Society of America
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Pronunciation Guide 
