Mineral Information and Data:

Aegirine-augite
(Ca,Na)(Fe3+,Fe2+,Mg)Si2O6 [CNMNC approved formula]

Named in 1950 and derived from its intermediate pyroxene composition. This is not an end-member species.

IMA status : Redefined IMA Approved; 1988 ()
CLASSIFICATION 
Dana
(8th edition) :
65.01.03b.02  
  (65) Inosilicate Single-Width Unbranched Chains, W=1
  (65.01) with chains P=2
  (65.01.03b) C2/c clinopyroxenes (intermediate clinopyroxenes)
  
Nickel-Strunz
(10th edition) :
09.DA.20
  (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: C 2/c
Unit cell: a = 9.663(3) Å, b = 8.813(3) Å, c = 5.2184(16) Å β = 106.40(2)°
Crystal Habit: Prismatic, Fibrous to Anhedral Grains
  
Color: Dark green, Black, Green, Pale greenish yellow, Greenish gray.
Diaphaneity: Translucent to opaque
Luster: Vitreous
Hardness (Mohs): 6
Measured Density: 3.4 - 3.6 g/cm3
Cleavage: {110} Very Good, {100} Parting
Tenacity: Brittle
Fracture: Splintery
  
  
Other Properties: Gemstone Unlikely Available.
Comments: Chemical composition intermediate between aegirine and augite.

 

Aegirine-augite
5 mm sized green anhedral aegirine-augite crystals in matrix.
Origin: Quarry near As-pier, Alnö, Sweden
Sample size: 8 x 11 cm
Photo: Diederik Visser

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