euhedral_001. Cut surface of an andesite from Quito, Ecuador. Rectangular white plagioclase and prismatic black hornblende phenocrysts stand out in a reddish tan groundmass. The plagioclase crystals average about 5 mm across.

euhedral_002. Large (cm-sized) euhedral alkali feldspar crystals stand out among smaller quartz and biotite grains in this photo of the 540 Ma Peninsula Granite near Cape Town, South Africa.

euhedral_003. Euhedral (diamond shaped cross section), white lawsonite crystals grew in this glaucophane schist from northwestern Syros, Greece. Although the lawsonite has been replaced by a very fine-grained mixture of other minerals, the euhedral shape of the original lawsonite remains as a pseudomorph. The pseudomorphs are 8-10 mm across.

euhedral_004. Euhdral brown staurolite crystals in a muscovite-quartz matrix have smooth, prismatic faces. Blue-gray kyanite laths and some of the red garnet crystals also show euhdral forms in this photograph of a Gassetts schist outcrop near Ludlow, VT, USA. The larger staurolite crystals are about 2 cm long.