Word Wednesday: Euhedral

Welcome to Word Wednesday, Wolfstone Rock Shop’s weekly look at the language of rocks, minerals, and gems.

Euhedral (yoo-HEE-drul) describes a crystal with well-developed natural faces that reflect its internal crystal structure.

Room to grow

A crystal is most likely to become euhedral when it grows freely into an open space, fluid-filled cavity, or pocket without being crowded by neighboring minerals. When crystal faces are only partly developed, geologists use subhedral. A grain with no recognizable faces is anhedral.

What it does—and does not—tell us

Sharp faces can make a specimen visually striking, but euhedral does not mean flawless, rare, or synthetic. Natural crystals can have growth interruptions, contact marks, inclusions, repairs, or later coatings. Manufactured objects can also imitate crystal shapes.

Collector tip

Look for consistent face geometry, natural growth texture, the relationship to matrix, and reliable locality information. Avoid judging authenticity from perfection alone.

See this texture and other mineral features in person at Wolfstone Rock Shop, 1857 N Casaloma Dr, Appleton, WI 54913. Inventory changes often, so call (920) 809-8577 if you are looking for a particular example.