Mineral Information and Data:

Clinoferrosilite
Fe2+SiO3 [CNMNC approved formula]

Named in 1935 as the monoclinic polymorph of ferrosilite.

IMA status : Approved Species 1988 ()
CLASSIFICATION 
Dana
(8th edition) :
65.01.01.02  
  (65) Inosilicate Single-Width Unbranched Chains, W=1
  (65.01) with chains P=2
  (65.01.01) P2/c clinopyroxenes
  
Nickel-Strunz
(10th edition) :
09.DA.10
  (09) Silicates
  (09.D) Inosilicates* Structural terminology per Liebau (1985)
  (09.DA) with 2-periodic single chains, Si2O6; pyroxene family
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Unit cell: a = 9.53Å, b = 9.21Å, c = 5.15Å β = 107.63°
Crystal Habit: As acicular crystals lacking terminal faces
Twinning: On {100}
  
Color: Colorless with amber tint
Diaphaneity: Semi-transparent
Luster: Vitreous
Hardness (Mohs): 5 to 6
Measured Density: 4.068 g/cm3
Cleavage: 1; {110} distinct
Streak: White
  
Polymorphism and Series: Dimorphous with ferrosilite
Geologic Setting: As acicular crystals in lithophysae in obsidian (Lake Naivasha, Kenya).
Mineral Association: Anorthoclase, magnetite, cristobalite, fayalite, biotite (Lake Naivasha, Kenya)
  

 

Clinoferrosilite
Lighter olive green translucent clinoferrosilite, with dark green diopside.
Origin: Merensky Reef, Western Bushveld Complex,
Northwest Province, South Africa
Sample size: 2.5 cm field of view. Excalibur Mineral specimen
Photo: Copyright © 2007, JGW

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