Perlite and Vermiculite

Perlite is derived from super-heating volcanic rock: heat is applied to expand (pop) volcanic glass in a furnace. It is a porous material which particles are lightweight, hard, roundish, and look like white granules. It provides aeration and drainage. Perlite has slightly alkaline pH.

Vermiculite is obtained by super-heating mica. It is a spongy material which particles are lightweight, soft, plate-like, and dark brown to golden brown in color. It provides aeration, moisture retention, and consistent release of added fertilizer. Vermiculite has close to neutral pH.