Leucite

Leucite properties at a glance

Geology & background

Leucite crystallizes from potassium-rich, silica-poor magmas and occurs as phenocrysts in young volcanic rocks such as leucitite and potassic lavas.

Leucite has long interested petrologists as an indicator of silica-poor potassic magmas, and it has been studied as a potential source of potassium and aluminum.

How to identify Leucite

• Look for rounded, near-spherical pale crystals with a trapezohedral form set in dark volcanic rock.
• Leucite is moderately hard, has very poor cleavage, and a conchoidal fracture.
• Distinguish it from garnet by its lower hardness and volcanic host, and from analcime by its crystal habit and association.

Where Leucite is found

Leucite occurs as phenocrysts in potassium-rich volcanic rocks, with notable localities in Italy, Germany, the United States, Uganda, and Australia.

How much is Leucite worth?

Value depends on crystal form, size, locality, aesthetics, damage, and provenance.

Common uses

• Petrological indicator
• Mineralogical study
• Experimental potassium source
• Collector specimens

Interesting facts

• The name leucite comes from a Greek word for white, reflecting its usual pale color.
• Leucite almost always forms equant trapezohedral crystals, a habit unusual among common minerals.
• It crystallizes in the cubic system at high temperature but inverts to tetragonal symmetry on cooling.
• Leucite is well known from the young volcanic rocks around Vesuvius and the Alban Hills in Italy.

Care & safety

Leucite is moderately hard but brittle, and crystals can chip or fracture if struck.

Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a proper respirator.

Related rocks & minerals

Nepheline Silicate Minerals Augite Minerals Analcime Minerals Sodalite Minerals Jadeite Silicate Minerals Kaolinite Silicate Minerals