Sandstone contains quartz and feldspar. It is often tan, brown, yellow and/or red. It may have a hardness of about 6.5. Sandstone cannot be described by a chemical formula because sandstone is not a pure substance. *

A-Sandstone is a mineral because minerals always have a hardness of 6.5.
B-Sandstone is a mineral because minerals are always made of quartz.
C-Sandstone is not a mineral because each mineral can only come in one color.
D-Sandstone is not a mineral because minerals are pure substances.