Mineral Information and Data:

Esseneite
CaFe3+AlSiO6 [CNMNC approved formula]

Named for Eric J. Essene, Professor at the University of Michigan, Ann Arbor, Michigan, USA, and discoverer of the first specimens.

IMA status : Approved Species 1987 (IMA1985-048)
CLASSIFICATION 
Dana
(8th edition) :
65.01.03a.06  
  (65) Inosilicate Single-Width Unbranched Chains, W=1
  (65.01) with chains P=2
  (65.01.03a) C2/c clinopyroxenes (Ca clinopyroxenes)
  
Nickel-Strunz
(10th edition) :
09.DA.15
  (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
Space group: C2/c
Unit cell: a = 9.79Å, b = 8.82Å, c = 5.37Å β = 105.81°
Crystal Habit: As prismatic crystals, up to 8 mm.
  
Color: Reddish brown, becoming darker with increasing Fe content.
Diaphaneity: Transparent in thin crystals
Luster: Vitreous
Hardness (Mohs): 6
Measured Density: 3.54 (calculated) g/cm3
Cleavage: Perfect on {110}
Streak: White
  
Geologic Setting: A high-temperature, low-pressure, oxidized and quenched crystallization product derived from fused sediments contiguous to naturally combusted coal seams.
Mineral Association: Anorthite, melilite, magnetite-hercynite, glass.
  

 

Esseneite
Yellow crusts and occasional crystals on matrix
Origin: Schöller mine, Libusin, Kladno, Czech Republic
Sample size: 3 x 5 cm
Photo: Diederik Visser

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