metamorphic
Carved ruby-in-zoisite frog
Ruby-in-zoisite (corundum, Al₂O₃, in zoisite, Ca₂Al₃(SiO₄)(Si₂O₇)O(OH))
AI-generated identification · may be incorrectA polished, carved specimen with apple-green zoisite, dark hornblende/biotite inclusions, and burgundy ruby patches. Zoisite has Mohs hardness 6–7; ruby is 9; vitreous to waxy luster, generally opaque, with no prominent cleavage.
Identified More metamorphic →
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Physical properties
A polished, carved specimen with apple-green zoisite, dark hornblende/biotite inclusions, and burgundy ruby patches. Zoisite has Mohs hardness 6–7; ruby is 9; vitreous to waxy luster, generally opaque, with no prominent cleavage.
Formation & geological history
Formed by metamorphism of aluminum- and calcium-rich rocks, commonly in Precambrian to Paleozoic metamorphic terranes; the best-known material comes from Tanzania. The frog shape is human-carved and polished.
Uses & applications
Primarily a decorative carving, lapidary object, and collector specimen; ruby-in-zoisite is occasionally used for ornamental stone and inexpensive cabochons, not typically fine jewelry.
Geological facts
Its green color is zoisite, while red areas are ruby rather than garnet. Black inclusions commonly consist of amphibole or biotite and help distinguish this material from green aventurine or jade.
Field identification & locations
Identify by the mottled green body, embedded red ruby grains, black inclusions, and relatively moderate weight; glassy uniform color suggests imitation. Common sources include Longido and Arusha, Tanzania.