Perlite is a kind of acidic lava that is erupted by volcanoes. The glassy rock that has been rapidly cooled is named for its pearl-fracture structure. Perlite mines include perlite, obsidian and rosin. The difference between the three is that perlite has a circular arc crack formed by condensation, called perlite structure, water content of 2 to 6%; rosin rock has a unique rosin luster, water content of 6 to 10%; black shale has glass Gloss and shell-like fracture, water content is generally less than 2%.
Wooden Interior Doors
Jiekai Industrial And Trading Co., Ltd. , http://www.gosdoors.com