1. Plural of greenstone; metamorphic or igneous rocks that are typically dark green in color, formed from the alteration of basic igneous rocks.
Usage: geology; technical
2. In New Zealand, a type of jade or nephrite stone that is green in color, traditionally used by Māori for tools and ornaments.
Usage: regional; New Zealand

Examples

• The geologist identified greenstones in the rock formation as evidence of ancient metamorphism.
• Greenstones are commonly found in areas with significant tectonic activity.
• The Archean greenstones of the Canadian Shield contain important mineral deposits.
• Māori artisans carved intricate designs into greenstones to create pendants and tools.
• The greenstone belts of Western Australia are among the oldest rock formations on Earth.