Human: What are the different types of sand? Assistant: 
The most common type of sand is quartz. Other types of sand include calcite, feldspar, and mica. Quartz sand is composed primarily of silicon dioxide (SiO2) and is usually white or light gray in color. Calcite sand is made up of calcium carbonate (CaCO3), and is usually a creamy yellow color. Feldspar sand is composed mostly of potassium feldspar and is usually brown or reddish-brown in color. Mica sand consists mainly of muscovite and biotite minerals, which gives it a silky feel to the touch.