Definition of greenstone

i. A field term applied to any compact dark-green altered or metamorphosed basic igneous rock (e.g., spilite, basalt, gabbro, diabase) that owes its color to the presence of chlorite, actinolite, or epidote.

Compare with: greenschist

ii. See: Nephrite

iii. An informal name for a greenish gemstone, such as fuchsite or chiastolite.

Ref: AGI

iv. Compact, igneous rocks that have developed enough chlorite in alteration to give them a green cast. They are mostly diabases and diorites. Greenstone is partially synonymous with trap. It is often used as a prefix to other rock names. The term is used frequently when no accurate determination is possible.

v. Includes rocks that have been metamorphosed or otherwise so altered that they have assumed a distinctive greenish color owing to the presence of one or more of the following minerals: chlorite, epidote, or actinolite.

vi. Freshly quarried stone containing quarry water.

Ref: Arkell

vii. Can. Generalized name given to Precambrian lavas.

Ref: Hoffman