igneous
Orbicular gabbro (likely leopardite)
Gabbro, chiefly plagioclase feldspar and pyroxene, with contrasting mafic and felsic orbicules
AI-generated identification · may be incorrectCoarse-grained, black-to-dark-green matrix with cream-white rounded patches; vitreous to dull luster, Mohs hardness about 6–7, massive texture, poor cleavage as a whole, and typical specific gravity around 2.8–3.1. The pattern is orbicular or mottled rather than a true crystal habit.
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Physical properties
Coarse-grained, black-to-dark-green matrix with cream-white rounded patches; vitreous to dull luster, Mohs hardness about 6–7, massive texture, poor cleavage as a whole, and typical specific gravity around 2.8–3.1. The pattern is orbicular or mottled rather than a true crystal habit.
Formation & geological history
A slowly cooled mafic intrusive rock formed deep in the crust, likely with later fluid-driven or magmatic segregation producing the pale orbicules; generally Precambrian to younger plutonic age depending on locality. Exact identification requires a fresh surface or thin section.
Uses & applications
Used mainly as a decorative and lapidary stone for polished slabs, cabochons, carvings, and display specimens; occasionally used as dimension stone. Collector value depends heavily on contrast, polish, provenance, and size.
Geological facts
Often marketed as leopardite, orbicular gabbro, or orbicular norite, though trade names can be inconsistent. Similar appearances may result from serpentinized ultramafic rocks or breccias.
Field identification & locations
Look for interlocking coarse grains and cream orbicules within a dense dark mafic matrix; it should not fizz with dilute acid and is much heavier than glass or plastic. Reported examples occur in Madagascar, Finland, South Africa, and other ancient igneous terranes.
