microlite

n. [ Micro- + -lite. ] (Min.) [ 1913 Webster ]

1. A rare mineral of resinous luster and high specific gravity. It is a tantalate of calcium, and occurs in octahedral crystals usually very minute. [ 1913 Webster ]

2. (Min.) A minute inclosed crystal, often observed when minerals or rocks are examined in thin sections under the microscope. [ 1913 Webster ]