Question

read the description below. use the definition of minerals to choose the correct statement about sandstone.
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.
choose one option
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.

Explanation:

A mineral is a naturally - occurring, inorganic, solid, with a definite chemical composition and ordered internal structure. Sandstone is not a pure substance (it contains quartz and feldspar) and cannot be described by a chemical formula. Option A is wrong because not all minerals have a hardness of 6.5. Option B is wrong because minerals are not always made of quartz. Option C is wrong because minerals can come in multiple colors. Option D is correct as minerals are pure substances and sandstone is not.

Answer:

D. Sandstone is not a mineral because minerals are pure substances.