A mineral consisting of ahomogeneous ground with crystals of some other mineral imbedded, giving to the mass a speckled complexion. One variety of Egyptian porphyry has a purple ground, whence the name of the species; but the homogeneous ground with imbedded crystals, being all that is essential to porphyry, its composition and colors are consequently various.

A mineral consisting of a homogeneous ground with crystals of some other mineral imbedded, giving to the mass a speckled complexion. One variety of Egyptian porphyry has a purple ground, whence the name of the species; but the homogeneous ground with imbedded crystals, being all that is essential to porphyry, its composition and colors are consequently various. Porphyry is very hard, and susceptible of a fine polish. Porphyry is composed of paste in which are disseminated a multitude of little angular and granuliform parts, of a color different from the ground.