千せん枚まい岩がん

せ

ん

ま

い

が

ん

Meanings

1

noun

phyllite

mineralogy

A fine-grained metamorphic rock intermediate between slate and schist. Used in geology and mineralogy.

粘ねん板ばん岩がん
粘板岩 (slate) is a lower-grade metamorphic rock with a more pronounced cleavage, while 千枚岩 (phyllite) has a slightly higher metamorphic grade and a silky sheen.
結けっ晶しょう片へん岩がん
結晶片岩 (schist) is a higher-grade metamorphic rock with visible mineral grains, whereas 千枚岩 (phyllite) is finer-grained.

The kanji 千枚 (thousand sheets) refers to the rock's fissile, layered appearance, and 岩 means rock. The reading is on'yomi.