Zircon

 Identification: Zircon is a zirconuim silicate, ZrSiO4. Though commonly colorless, especially in Florida sands, zircon may be red, blue, brown, or lavender. The streak is colorless, the specific gravity 4.4 to 4.8 and the hardness 7.5.  In Florida, zircon occurs as sand-size particles and may be distinguished from quartz by its brilliant luster and smooth crystal faces as seen with the aid of a microscope.
Occurrence: Zircon is a heavy mineral in Florida's Recent and ancient beach sands.
Use: Zircon, because of its ability to withstand very high temperatures, is made into bricks and cements used in foundries and in furnaces for making aluminum and glass.