Mineral Information and Data:

Akermanite
Ca2MgSi2O7 [CNMNC approved formula]

Named after Anders Richard Åkerman (1837-1922), Swedish metallurgist.

IMA status : Valid species (Pre-IMA 1884) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
55.04.01.01  
  (55) Sorosilicate Si2O7 Groups, Generally with No Additional Anions
  (55.04) with cations in [8] and lower coordination
  (55.04.01) Melilite group
  
Nickel-Strunz
(10th edition) :
09.BB.10
  (09) Silicates
  (09.B) Sorosilicates (dimer) structures
  (09.BB) Si2O7 groups, without non-tetrahedral anions; cations in tetrahedral [4] and greater coordination
  
Crystal system: Tetragonal System
Point group (H-M): 42m (or 4 2m) — scalenohedral
Unit cell: a = 7.829 Å, c = 5.005 Å
Crystal Habit: Crystals short prismatic to thin tabular; commonly massive granular
Twinning: On {100} and {001}, cruciform
  
Color: Colorless, grayish, green, brown
Diaphaneity: Transparent to translucent
Luster: Vitreous to resinous
Hardness (Mohs): 5 - 6
Measured Density: 2.944 g/cm3
Cleavage: 2; {001} distinct, {110} indistinct
Tenacity: Brittle
Streak: White
  
Polymorphism and Series: Forms a series with gehlenite.
Geologic Setting: A product of contact metamorphism of siliceous limestones and dolostones, and in rocks of the sanidinite facies. Also forms from alkalic magmas rich in calcium.
Mineral Association: Monticellite, wollastonite, spurrite, larnite, merwinite, "fassaite," grossular,
diopside, forsterite
  

 

Akermanite
Greyish-green crystals in rock with fassaite
Origin: Casa Collina Quarry, Pitigliano, Grosseto, Italy
Sample size: 3 x 5 cm
Photo: Diederik Visser

<<< BACK TO MINERAL SEARCH