Talc

Nogami-Shimogo, Nagatoro city, Chichibu county, Saitama pref., Japan

Field of view: 30 mm. Talc associated with dolomite. The columnar group of white fibers at the left is talc. The grayish-white part exhibiting perfect cleavage at the right is dolomite.

Recovered from serpentinite in an accretionary complex subjected to Greenschist facies high-pressure metamorphic rock.

Combination of dolomite and talc is explained by the CO₂ fluid in fissures of serpentinite:

2Mg₃Si₂O₅(OH)₄ (Serpentine) + 3CO₂ = Mg₃Si₄O₁₀(OH)₂ (Talc) + 3MgCO₃ (Magnesite component in Dolomite) + 3H₂O

Talc from this location was described in 1913.

Other localities

List of Japanese talc localities

Miyazawa (Serpentinite, Fibrous)
Kurotani Valley (Serpentinite, Massive)
Ninomiya (Serpentinite, Massive)