Vermiculite is a kind of layered mineral that contains Mg and degenerates secondarily from hydrated aluminum silicates. It is usually formed by weathering or hydrothermal alteration of biotite or phlogopite. Categorized by stages, vermiculite can be divided into unexpanded vermiculite and expanded vermiculite. Categorized by color, it can be divided into golden and silver (ivory). Vermiculite has excellent properties such as heat insulation, cold resistance, anti-bacteria, fire prevention, water absorption and sound absorption, etc. When baked for 0.5 ~ 1.0 minutes under 800 ~ 1000 ℃, its volume can be increased rapidly by 8 to 15 times, up to 30 times, with the color changed into gold or silver, producing a loose-textured expanded vermiculite which is not anti-acid and poor in electric performance. Vermiculite after the expansion process will take on layered flaky shape, with the proportion generally being 100-200kg/ m³( Due to the huge volume of expanded vermiculite, the transportation cost would be quite huge, so the exported vermiculite is usually types of unexpanded ).