It is formed of quartz particles (sand) and is structurally stable, usually in light brown or red, mainly containing silicon, calcium, clay and iron oxide. Sandstone is a kind of sedimentary rock, which is mainly composed of sand grains. The content of sand grains is more than 50%. Most sandstones are made up of quartz or feldspar. Acoustic Panel,Wood Sound Panels,Sound Panels For Walls,Acoustic Sound Panels Guangzhou MQ Acoustic Materials Co., Ltd , https://www.movablepartitionwall.com