Mineral Information and Data:

Katophorite
NaNaCa[Fe2+4(Al,Fe3+)](Si7Al)O22(OH)2 [CNMNC approved formula]

Named from the Greek for "carrying down", in allusion to its volcanic origin. First published in 1894. Redefined per nomenclature of amphiboles (IMA, 1997).

IMA status : Redefined IMA Approved; 1997 ()
CLASSIFICATION 
Dana
(8th edition) :
66.01.03b.12  
  (66) Inosilicate Double-Width Unbranched Chains, W=2
  (66.01) with P=2 amphibole configuration
  (66.01.03b) Group 3, the sodic-calcic amphiboles
  
Nickel-Strunz
(10th edition) :
09.DE.20
  (09) Silicates
  (09.D) Inosilicates* Structural terminology per Liebau (1985)
  (09.DE) with 2-periodic double chains, Si4O11; Clinoamphiboles
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Space group: C2/m
Unit cell: a = 10.019(2)Å, b = 18.036(7)Å, c =5.286(3)Å; β=104:98(3)° Z = 2
Crystal Habit: Prismatic, granular, also as fibrous aggregates or dendrites and skeletal crystals. Commonly rimming other minerals.
Twinning: Parallel to {100}
  
Color: Black, dark green-black, bluish black; reddish yellow, bluish green in thin section
Diaphaneity: Transparent to translucent
Luster: Vitreous
Hardness (Mohs): 5 - 6
Measured Density: 3.2 - 3.5 g/cm3
Cleavage: Perfect on {110}, intersecting at ~56° and ~124°; parting on {010}
Tenacity: Brittle
  
Polymorphism and Series: Forms a series with magnesiokatophorite.
Geologic Setting: In alkalic volcanic and plutonic igneous rocks; in blueschist facies jadeitites.
Mineral Association: Arfvedsonite, aegirine, nepheline, pyroxenes, eckermannite, chromite
  

 

Katophorite
Dark green katophorite crystals associated with yoshimuraite.
Mineral identification confirmed by a single-crystal X-ray diffraction only.
Origin: Toguchi mine, Shidara, Kitashidara-Gun, Aichi, Japan.
Photo: © RRUFF Project

 

Katophorite
zoom of a crystal fragment from above.

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