May 31, 2015· Rock is a solid heterogeneous mixture of one or more minerals. For example, granite is a mixture of the minerals quartz, feldspar, and biotite. A mineral is a naturally occurring solid that has a crystalline structure and a definite chemical formula. For example, gibbsite is a mineral of aluminium with the formula "Al(OH)"_3. An ore is a rock that contains minerals in concentrations that are ...