noun
Iceland spar
A transparent variety of calcite used in optical instruments; a mineralogy term.
氷州石は複屈折の実験によく使われる。
Iceland spar is often used in birefringence experiments.
The name 氷州石 literally means 'Iceland stone', from 氷州 (Iceland) + 石 (stone). The exact historical derivation is uncertain, but it is a direct calque of the English term 'Iceland spar'.