Vermiculite is a kind of clay mineral similar to montmorillonite. It is a layered silicate. It is generally formed by hydrothermal alteration or weathering of biotite. It sometimes appears in the form of thick biotite (which is the biotite illusion of vermiculite), and sometimes in the form of soil. When vermiculite is heated to 300â??, it expands 20 times and bends. Vermiculite is a bit like a leech, hence its name. Vermiculite is generally brown, yellow, dark green, with an oily sheen, turning gray when heated. After roasting at high temperature, the volume of vermiculite slices can rapidly expand 6-20 times, and the specific gravity after expansion is 60-180kg/m3, which has strong thermal insulation performance. Our customers in Taiwan, China, who specialize in wholesaling horticulture and refractory materials, recently acquired expanded vermiculite from our inventory.