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Webster 1913 Edition

Noun.

[See

(Min.)

A mineral which is opaque in its natural state, but is said to change its color and become transparent by heat.

Noun.

[Gr., fire; clear.] A mineral which in its natural state is opake, but rendered transparent by heat.

pyrophane

(mineralogy) A mineral which is opaque in its natural state, but is said to change its color and become transparent by heat.