A particular kind of such material. Cf. stone, n. 2c.

(a) a superficial deposit of rock; (b) rock that forms or formerly formed part of the earth's mantle.

In any of several theories of the structure of the earth: the lower part of the earth's crust, composed of relatively dense rocks rich in silica and…

The discontinuous upper layer of the earth's crust represented by the continental masses, which are composed of relatively light rocks rich in silica…

The material in the asthenosphere.

A material which (according to some models) is regarded as typical of the earth's upper mantle, corresponding in composition to a mixture of basalt…