Word Wednesday

Breccia is a rock made of angular fragments cemented together, preserving evidence of breakage and later geological repair.

Drusy describes a glittering coating of tiny crystals lining a rock surface, cavity, or earlier mineral.

Asterism is the star-shaped light effect seen in certain sapphires, rubies, garnets, quartz, and other gemstones.

Tenebrescence is a reversible light-triggered color change found in hackmanite and a few other minerals.

Euhedral crystals develop clear natural faces because they had room to grow without being crowded.

Pleochroism is the display of different colors when certain crystals are viewed from different directions.

Conchoidal fracture creates smooth, curved, shell-like breaks in quartz, obsidian, glass, and other materials.

A pseudomorph is a mineral that keeps another mineral’s outward shape after replacement or alteration.

Learn why chatoyant stones display a bright moving band of light known as the cat’s-eye effect.

Word Wednesday defines botryoidal, the rounded, grape-like mineral texture seen in hematite, malachite, chalcedony, and other specimens.