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Mount Kinsho

Kiroko, Ogawa city, Hiki county, Saitama pref., Japan

Occurrence

Titanium type rare-element pegmatite

Pegmatite in the Early Triassic (250 Ma ) Kinshozan Granodiorite overlying the Cretaceous Sambagawa Metamorphic Rocks through a low angle thrust fault. This structure is interpreted as a nap. Kinshozan granodiorite is interpreted as a member of igneous rocks of an island arc from its chemical composition. The age of granodiorite was determined by K-Ar radiometric dating of hornblende.

Mount Kinsho

Outcrop of a pegmatite vein in Kinshozan Granodiolite. The white vein from right to left is pegmatite. It is composed of quartz and feldspar with minor amount of muscovite. The surrounding host is granodiolite, and there is no specific structures at the boundary between granodiolite and pegmatite. A small fault cuts the pegmatite at the left end of the photograph.

Reported Minerals

  • Muscovite
  • Almandine

Mineral Assemblages

  • Quartz - Feldspar - Muscovite - Almandine
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