Coal is not considered a mineral because it does not have a solid, uniform crystal structure, meaning it doesn't fit the primary definition of a mineral. Coal is primarily made of carbon, but its properties can vary even... More » Science Earth Science Geology

Coal is not a mineral because it is organic, and minerals are inorganic. Minerals have a repeating crystalline structure and a homogeneous chemical profile. Coal has neither. It forms over millions of years from the comp... More »

Coal is considered a non-renewable resource because the earth cannot replenish it. Geologic heat and pressure work on organic decomposing materials to create coal. This process takes millions of years. More »

The main difference between quartz crystal and glass is that glass does not have a crystalline structure. Glass is also made with additives that quartz crystal does not contain. More »

Crystals grow in different shapes because of the internal symmetry of the crystal and the growth rate along the direction of the crystal. The arrangement of the atoms in a crystal is called a lattice. In a perfect enviro... More »

The primary difference between diamond and graphite is the way their carbon atoms are arranged to form their physical crystal structures. The arrangement of carbon atoms in diamonds makes them bond together strongly, whi... More »

Colored diamonds form under the same conditions as clear diamonds, but their colorations are due to chemical impurities or structural imperfections within the crystal lattice. Although all diamond color varieties are pos... More » Science Earth Science Geology