igneous
Amethyst-rich vesicular volcanic rock (probable amethyst basalt/scoria)
Quartz (SiO₂) in vesicular basaltic volcanic rock; precise identification requires testing
AI-generated identification · may be incorrectPurple, uneven, likely druzy quartz lining vesicles in a dark gray porous host; quartz hardness 7, vitreous luster, no cleavage, hexagonal crystals, specific gravity ~2.65. The host appears fine-grained and highly vesicular.
Identified More igneous →
Explore Amethyst-rich vesicular volcanic rock (probable amethyst basalt/scoria) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Purple, uneven, likely druzy quartz lining vesicles in a dark gray porous host; quartz hardness 7, vitreous luster, no cleavage, hexagonal crystals, specific gravity ~2.65. The host appears fine-grained and highly vesicular.
Formation & geological history
Formed when gas-rich basaltic lava cooled rapidly, leaving cavities later lined or filled by silica-bearing fluids and purple amethyst. Likely Cenozoic or younger, though the specimen’s age cannot be determined visually.
Uses & applications
Primarily a collector specimen or decorative stone; amethyst-bearing basalt can be cut or polished but is generally not used as structural aggregate when strongly vesicular.
Geological facts
The purple color in amethyst usually results from iron impurities and natural irradiation. The rough, cavity-rich texture distinguishes it from massive amethyst geodes and from purple glass or slag.
Field identification & locations
Look for a porous volcanic matrix, sharp drusy quartz sparkle, glassy fracture, and quartz hardness; a steel knife should not scratch the purple crystals. Common sources include Brazil, Uruguay, Mexico, and parts of the western United States.
