metamorphic
Greenstone pebble
Likely chlorite- and/or actinolite-bearing metamorphic rock; exact composition cannot be determined from the image.
AI-generated identification · may be incorrectDark olive-green, smooth and rounded, with thin pale mineral veins. Hardness and luster vary with composition; the veins may be quartz or calcite, and the rock’s crystal structure is not identifiable from the photo.
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Physical properties
Dark olive-green, smooth and rounded, with thin pale mineral veins. Hardness and luster vary with composition; the veins may be quartz or calcite, and the rock’s crystal structure is not identifiable from the photo.
Formation & geological history
Likely formed when mafic igneous rock was altered by low-grade metamorphism and later rounded by water. Its age and precise formation environment cannot be determined visually.
Uses & applications
Commonly collected as a beach or river pebble; decorative uses include landscaping and polished stone crafts.
Geological facts
The name “greenstone” describes a color and rock family, not one specific mineral or composition.
Field identification & locations
Look for the green matrix and contrasting veins; similar pebbles occur on beaches and in stream deposits sourced from metamorphic terrains. A hand lens or mineral tests would help narrow the identification.
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