Mineral Information and Data:

Amesite
Mg2Al(SiAl)O5(OH)4 [CNMNC approved formula]

Named to honor James Ames, a mine owner.

IMA status : Valid species (Pre-IMA 1876) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
71.01.02c.01  
  (71) Phyllosilicate Sheets of Six-Membered Rings
  (71.01) with 1:1 layers
  (71.01.02c) Serpentine group (Amesite subgroup)
  
Nickel-Strunz
(10th edition) :
09.ED.15
  (09) Silicates
  (09.E) Phyllosilicates
  (09.ED) Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
  
Crystal system: Triclinic System
Point group (H-M): 1 — pedial
Unit cell: a = 5.307 Å, b = 9.195 Å, c = 14.068 Å, a = 90.09°, b = 90.25°, g = 89.96°
Crystal Habit: Crystals prismatic or as pseudo-hexagonal plates; foliated aggregates
Twinning: Common as six-fold sector twins on {001} and polysynthetic twins parallel to {010} prism edges
  
Color: Pale green, white
Diaphaneity: Translucent
Luster: Pearly on cleavage
Hardness (Mohs): 2.5 - 3
Measured Density: 2.78 g/cm3
Cleavage: 1; {001} perfect
Tenacity: Brittle
Streak: White with pale green tint
  
Polymorphism and Series: 2H; 2H2; 6R polytypes.
Geologic Setting: A product of low-grade metamorphism of Al, Mg-rich rocks
Mineral Association: Vesuvianite, chlorite (Pensacola Mountains, Antarctica); magnetite, rutile, diaspore (Chester, Massachusetts, USA); grossular, calcite, diopside, clinozoisite (Black Lake, Canada)
  

 

Amesite
Chromium amesite
Origin: Sarany, Ural, Russia
Sample size: 4 x 2 x 2 cm
with 4 mm deep purple prismatic crystals in matrix
Photo: Tom Loomis

 

Amesite
(zoom-in of above)

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