Euhedral and anhedral

Idiomorphic (from Greek idios "own", morphé "shape" ) is a name for a mineral that has its own form of fully developed. This means that it has well-developed crystal faces and a characteristic geometry. The natural shape of a mineral is directly dependent on its crystallographic structure. Euhedral minerals form when they are not spatially concentrated in their growth. Examples are divide minerals that grow in cavities in the rock, or early from a molten rock ( magma ) crystallizing minerals ( phenocrysts in volcanic rocks ).

The opposite is idiomorphic xenomorph ( alien multiform ). Only partially intrinsically protean minerals are called hypidiomorph.

Euhedral quartz crystals

Pseudo - leucite from Brazil

Euhedral apatite crystals on feldspar

Sharply defined euhedral phenocrysts in igneous rocks ( thin section )

In contrast: Xenomorpher quartz ( gray ) in a rock next to feldspar (white) and mafic minerals ( black)

• Mineralogy