Minerals can form on the surface through evaporation of solutions containing dissolved minerals. Minerals can form beneath the surface when dissolved elements and compounds leave a hot water solution or when materials melted in magma/ lava then cools & hardens.
There are approximately 3800 known minerals. About 30 to 50 new minerals are described and one or two minerals are discredited each year. The most complete listing of minerals is J. Mandarino Fleischer’s Glossary of Mineral Species 1999 published by the Mineralogical Record.
As volcanoes erupt, they build up layers of lava that may eventually break the water’s surface. When the tops of the volcanoes appear above the water, an island is formed. While the volcano is still beneath the ocean surface, it is called a seamount. Oceanic islands can form from different types of volcanoes.
The most common cause of color in gemstones is the presence of a small amount of a transition metal ion. Most gemstones are allochromatic, meaning that they are colored by impurities or trace elements in their crystal structure.