igneous
Rhyolite Cross Pendant
Rhyolite (High-silica volcanic rock)
Hardness: 6-7 (Mohs scale), Color: Pinkish-red, tan, and grey banding/mottling, Luster: Dull to sub-vitreous, Crystal structure: Aphanitic or porphyritic (fine-grained matrix), Specific Gravity: 2.4-2.6
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Pinkish-red, tan, and grey banding/mottling, Luster: Dull to sub-vitreous, Crystal structure: Aphanitic or porphyritic (fine-grained matrix), Specific Gravity: 2.4-2.6
Formation & geological history
Formed from the rapid cooling of silica-rich (felsic) lava at or near the Earth's surface. This specimen likely dates from the Cenozoic era and shows flow banding or hydrothermal alteration common in volcanic fields.
Uses & applications
Used primarily for lapidary work, jewelry (pendants, beads), and as a decorative stone. Because of its toughness, it survives well in tumbled and carved forms.
Geological facts
Rhyolite is the volcanic equivalent of granite. The pink and red hues often come from trace amounts of iron oxides or manganese within the silicate matrix. Carving these into shapes like crosses is common in artisanal craft markets.
Field identification & locations
Identify by its fine-grained texture, banded or mottled colors, and lack of visible large crystals compared to granite. It is commonly found in volcanic regions of the American Southwest, Mexico, and the Andes.
