Large crystals found in geodes and other rocks are relatively rare ... Minerals and gems are classified by their physical properties, including hardness, luster, color, density, and magnetism.

Their findings, published in Science Advances, suggest that the properties of rocks may contribute equally to the generation ...

Petrology is the study of rocks - igneous, metamorphic, and sedimentary - and the processes that form and transform them. Mineralogy is the study of the chemistry, crystal structure and physical ...