Metamorphic
Greenstone
Chlorite schist or metabasalt depending on specific composition
Hardness: typically 3-5 on Mohs scale depending on specific minerals present. Color: Various shades of green, dark green, to grayish-green. Luster: Dull to slightly waxy. Cleavage: Poor, typically massive or foliated if schistic. Specific gravity: approx. 2.8-3.3.
- Color
- Various shades of green, dark green, to grayish-green
- Luster
- Dull to slightly waxy
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Physical properties
Hardness: typically 3-5 on Mohs scale depending on specific minerals present. Color: Various shades of green, dark green, to grayish-green. Luster: Dull to slightly waxy. Cleavage: Poor, typically massive or foliated if schistic. Specific gravity: approx. 2.8-3.3.
Formation & geological history
Formed through low-grade regional metamorphism of mafic to ultramafic igneous rocks (like basalt). Common in ancient greenstone belts of Archean and Proterozoic age.
Uses & applications
Used historically by indigenous peoples for tools and carvings due to its toughness. Today used as crushed stone for construction, road building, and occasionally for carving or local landscaping.
Geological facts
Greenstone belts hold some of the oldest rocks on Earth and are often associated with valuable ore deposits, including gold, silver, copper, and zinc.
Field identification & locations
Identified by its distinctive green color resulting from minerals like chlorite, epidote, or actinolite. Often found rounded in riverbeds or beaches where it has been transported and smoothed by water.
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