Mineral Information and Data:

Lizardite
Mg3Si2O5(OH)4 [CNMNC approved formula]

Named from the locality: The Lizard, Cornwall, England.

IMA status : Valid species (Pre-IMA 1956) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
71.01.02b.02  
  (71) Phyllosilicate Sheets of Six-Membered Rings
  (71.01) with 1:1 layers
  (71.01.02b) Serpentine group (Lizardite 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: Trigonal System
Point group (H-M): 3m — ditrigonal-pyramidal
Unit cell: a = 5.325 Ǻ, c = 7.259 Ǻ
Crystal Habit: Massive, fine- to coarse-grained, compact; small scales
  
Color: Green, green-blue, white
Diaphaneity: Translucent
Luster: Waxy
Hardness (Mohs): 2.5
Measured Density: 2.55 to 2.60 g/cm3
Cleavage: 1; {0001} perfect
Tenacity: Crystals are easily bent
  
Polymorphism and Series: Polymorphous with antigorite, clinochrysotile, orthochrysotile, and parachrysotile.
Forms a series with nepouite.
Geologic Setting: Typically a product of retrograde metamorphism, replacing olivine, orthopyroxene, or other minerals in ultramafic igneous rocks.
Mineral Association: Chrysotile, brucite, magnetite
  
Synonyms/varieties: Green variety bastite, Al-lizardite, Nickeloan Lizardite
Comments: Polytypes :1A, 6A, 2H.

 

Lizardite
Green variety bastite partly after orthopyroxene in harzburgite matrix
Origin: Baste, south of Bad Harzburg, Harz, Germany
Sample size: 5 x 11 cm
Photo: Diederik Visser

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