TrekGEO > Mineral Trail > Tohoku region > Miyagi pref. > Adachi

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Motoisago, Kawasaki city, Shibata county, Miyagi pref., Japan


Hornblende-hornfels facies contact metamorphic rocks

Accidental lithic fragments, Ceramisite, included as volcanic blocks in a Adachi-Medeshima Pumice Bed erupted from Adachi Volcano in the Late Pleistocene (0.06-0.08 Ma). Accidental lithic fragments have been subjected to hornblende-hornfels facies contact metamorphism in magma chamber. Cummingonite and cordierite were formed in tonalite-origin fragments by contact metamorphism. Cummingtonite is also abundant in pumice.


Outcrop of the Adachi-Medeshima pumice bed erupted from Adachi Volcano. The gray block above the coin is an accidental lithic fragment of tonalite containing cordierite. The white parts in the fragment are quartz. The white parts around the fragment are composed of pumice, and black grains in pumice are cummingtonite.

Reported Minerals

Mineral Assemblages

  • Quartz - Feldspar - Cummingtonite
  • Quartz - Feldspar - Cordierite
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