Mineral Information and Data:

Chondrodite
Mg5(SiO4)2F2 [CNMNC approved formula]

Named from the Greek for "grain" in allusion to its habit of occurring in isolated grains.

IMA status : Valid species (Pre-IMA 1817) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
52.03.02b.02  
  (52) Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O
  (52.03) with cations in [6] coordination only
  (52.03.02b) Humite group (Chondrodite series)
  
Nickel-Strunz
(10th edition) :
09.AF.45
  (09) Silicates
  (09.A) Nesosilicates (Isolated tetrahedron) structures
  (09.AF) Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Unit cell: a = 10.26 Ǻ, b = 4.73 Ǻ, c = 7.87 Ǻ, β = 109.0°
Crystal Habit: Crystals varied, highly modified; massive
Twinning: Common on {001}
  
Color: Light yellow, yellow, brown, red; in thin section, pale yellow or brown to colorless
Diaphaneity: Transparent to translucent.
Luster: Vitreous to resinous
Hardness (Mohs): 6 to 6.5
Measured Density: 3.16 to 3.26 g/cm3
Cleavage: 1; {100} indistinct
Tenacity: Brittle
Fracture: Subconchoidal to uneven
Streak: White-gray, yellow
  
Polymorphism and Series: Forms a series with alleghanyite.
Geologic Setting: In contact metamorphic zones, in limestones and dolostones, associated with felsic
to alkalic plutonic rocks, especially with Fe-B-F metasomatism; in a carbonatite
Mineral Association: Phlogopite, spinel, magnetite, grossular, wollastonite, forsterite, monticellite,
cuspidine, diopside, calcite
  
Synonyms/varieties: Brocchite Brucite (of Gibbs), Condrodite, Maclureite (of Nuttall), Prolectite
Other Properties: Gemstone Extremely Rare.

 

Chondrodite
Chondrodite on calcite
Origin: Mogok, Burma
Sample size: 2.5 x 2.25 x 1.5 cm
Photo: Rob Lavinsky

 

Chondrodite
(zoom-in of above)

 

Chondrodite
Origin: Tilly Foster Mine, Brewster, Putnam County, New York, U.S.A.
Sample size: 5 x 3 x 2.5 cm
Photo: Rob Lavinsky

 

Chondrodite
(zoom-in of above)

 

Chondrodite
Chondrodite on schist
Origin: Ladjuar Madan, Kokcha Valley, Afghanistan, Asia
Sample size: 2.5 x 1.7 x 1 cm
Photo: John Veevaert, Trinity Mineral Co

 

Chondrodite
(zoom-in of above)

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