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Protoanthophyllite

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Takase mine, Okayama Prefecture, Chugoku Region, Honshu Island, Japan
© 2008, JGW

Formula:
☐[Mg
 
2
][Mg
 
5
][(OH)
 
2
|Si
 
8
O
 
22
]
System:OrthorhombicColour:colourless to white
Hardness:6
Name:Named for being a protoamphibole polymorph of Anthophyllite.


Amphibole Group.

Classification of Protoanthophyllite

IMA status:Approved 2001
Explanation of status:IMA 2001-065
Strunz 8th edition ID:8/F.12-140
Nickel-Strunz 10th (pending) edition ID:9.DD.05

9 : SILICATES (Germanates)
D : Inosilicates
D : Inosilicates with 2-periodic double chains, Si4O11; Orthoamphiboles
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Type Occurrence of Protoanthophyllite

Type Locality:Takase mine, Okayama Prefecture, Chugoku Region, Honshu Island, Japan
General Appearance of Type Material:acicular prisms to 10 mm
Place of Conservation of Type Material:Natural Science Museum, Tokyo
Geological Setting of type material:contact-metamorphosed serpentinite
Associated Minerals at type locality:
TremoliteTalcSerpentine GroupForsteriteChlorite Group

Occurrences of Protoanthophyllite

Geological Setting:metamorphosed serpentinites

Physical Properties of Protoanthophyllite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:colourless to white
Streak:white
Hardness (Mohs):6
Tenacity:Brittle
Cleavage:Perfect
on {110}
Density (measured):2.98 g/cm3

Crystallography of Protoanthophyllite

Crystal System:Orthorhombic
Class (H-M):mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:a = 9.355Å, b = 17.93Å, c = 5.311Å
Ratio:a:b:c = 0.522 : 1 : 0.296
Unit Cell Volume:V 890.84 ų (Calculated from Unit Cell)
Morphology:prismatic crystals, elongated parallel to [001]
X-Ray Powder Diffraction:
d-spacingIntensity
8.32 (70)
3.66 (100)
3.08 (80)

Chemical Properties of Protoanthophyllite

Formula:
☐[Mg
 
2
][Mg
 
5
][(OH)
 
2
|Si
 
8
O
 
22
]
Essential elements:
All elements listed in formula:H, Mg, O, Si
Common Impurities:Na,Mn,Ni,Al

Relationship of Protoanthophyllite to other Species

Related Minerals - Nickel-Strunz Grouping):
9.DD.05Anthophyllite
☐[Mg
 
2
][Mg
 
5
][(OH)
 
2
|Si
 
8
O
 
22
]
9.DD.05Ferro-anthophyllite
☐[Fe
2+
2
][Fe
2+
5
][(OH)
 
2
|Si
 
8
O
 
22
]
9.DD.05Ferrogedrite
☐[Fe
2+
2
][Fe
2+
3
Al
 
2
][(OH)
 
2
|Al
 
2
Si
 
6
O
 
22
]
9.DD.05Gedrite
☐[Mg
 
2
][Mg
 
3
Al
 
2
][(OH)
 
2
|Al
 
2
Si
 
6
O
 
22
]
9.DD.05Holmquistite
☐[Li
 
2
][Mg
 
3
Al
 
2
][(OH)
 
2
|Si
 
8
O
 
22
]
9.DD.05Protoferro-anthophyllite
☐[Fe
2+
2
][Fe
2+
5
][(OH)
 
2
|Si
 
8
O
 
22
]
9.DD.05Protomangano-ferro-anthophyllite
☐[Mn
2+
2
][Fe
2+
5
][(OH)
 
2
|Si
 
8
O
 
22
]
9.DD.05Sodicanthophyllite
[Na][NaMg][Mg
 
5
][(OH)
 
2
|Si
 
8
O
 
22
]
9.DD.05Sodic-ferro-anthophyllite
[Na][NaFe
2+
 
][Fe
2+
5
][(OH)
 
2
|Si
 
8
O
 
22
]
9.DD.05Sodic-ferrogedrite
[Na][Fe
2+
2
][Fe
2+
4
Al][(OH)
 
2
|Al
 
2
Si
 
6
O
 
22
]
9.DD.05Sodicgedrite
[Na][Mg
 
2
][Mg
 
4
Al][(OH)
 
2
|Al
 
2
Si
 
6
O
 
22
]
9.DD.05Ferroholmquistite
☐[Li
 
2
][Fe
2+
3
Al
 
2
][(OH)
 
2
|Si
 
8
O
 
22
]

Other Names for Protoanthophyllite

German names:
Protoanthophyllit
Japanese names:
プロト直閃石
Russian names:
Протоантофиллит
Spanish names:
Protoanthophyllita

Other Information

Fluorescence in UV light:none
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 Protoanthophyllite

Reference List:Sueno, S., Matsuura, S., Gibbs, G.V., and Boisen, M.B., Jr. (1998) A crystal chemical stud of protoanthophyllite: orthoamphiboles with the protoamphibole structure. Physics and Chemistry of Minerals: 25: 366-377.

Konishi, H., T.L. Groy, I. Dodony, R. Miyawaki, S. Matsubara and P.R. Buseck (2003): "Crystal structure of protoanthophyllite: a new mineral from the Takase ultramafic complex, Japan" - American Mineralogist: 87: 1096-1103.

Konishi, H. et al. (2003): American Mineralogist: 88: 1718-1723.

Hawthorne, Frank C., and Roberta Oberti (2006), On the classification of amphiboles: Canadian Mineralogist:
44(1): 1-21.

Internet Links for Protoanthophyllite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Protoanthophyllite in the Natural History Museum (London) online catalogue
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    Localities for Protoanthophyllite

    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Japan
     
    • Honshu Island
      • Chugoku Region
        • Okayama Prefecture
    		Konishi, H., et al. (2003): Am.Min. 88, 1718–1723
    Lapis 29(1), 47 (2004)
      • Tohoku Region
        • Iwate Prefecture
          • Kitakami Mts
    		Lapis 29(1), 47 (2004)
    Mineral and/or Locality
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