Orbicular Granite

Physical Properties

Hardness: 6-7 (Mohs scale), Color: black, tan, and cream mottled/circular patterns, Luster: Vitreous to dull when unpolished, Crystal Structure: Phaneritic with orbicles, Cleavage: Imperfect, Specific Gravity: 2.6-2.7

Formation & Geological History

Formed through the cooling of magma deep underground where nucleated rhythmic growth of minerals (plagioclase, biotite, hornblende) occurs around a seed crystal or rock fragment during the crystallization process.

Uses & Applications

Used primarily as decorative stones in jewelry, lapidary arts, high-end construction countertops, and as prized geological specimens for collectors.

Geological Facts

Orbicular rocks are exceptionally rare; less than 1% of granite occurrences worldwide exhibit this specific orbicular texture, making them highly sought after by museums and private collectors.

Field Identification & Locations

Identify by looking for distinct circular or 'eye-like' mineral bands within a granitic matrix. Commonly found in specific localities like Western Australia, Chile, and parts of the United States (California/Idaho).

Identified on: 4/25/2026

Mode: Standard