[Chemical name] silicon dioxide [Chemical formula] SiO2 [Common or alternative name] Sand, silica [Source and description] 
Quartz sand is relatively pure silicon dioxide and is available at many building supply stores and also aquarium shops. Often found sorted by particle size for use in sandblasting. Micrometre sized particles are used as a filler in rubbers, plastics, and mold making materials and may be available in hobby shops as Min-u-Sil brand. Available in a porous, amorphous form as the silica desiccant packets found in many sealed food envelopes, electronics boxes, and other packaging. New desiccant packets are often available from local photography stores which cater to the at-home darkroom crowd. Non-porous amorphous silica is industrially known as Cab-o-Sil. Fairly pure quartz (silica) crystal can be found as one of the rock varieties in many "fill your bag with treasure" stands at tourist-oriented gift shops.[citation needed]