Mineral specimens are small pieces or samples of the mineral, or rock that has a specific chemical composition and ordered atomic arrangement. They are purchased by collectors and those who want to study geology, mineralogy and mining. The hobby of collecting mineral specimens is called rock hounding, and there are numerous clubs around the world dedicated to it. Some of the more commonly known but rare and sometimes valuable minerals are amethyst, copper, diamond, and turquoise.
Amethyst is a variety of quartz (SiO2) that obtains its purple color from iron atoms in a trigonal crystal matrix. They are mined commercially in Brazil and Uruguay. The birthstone for February, it is a popular gemstone purchased by jewelers as well as collectors.
The state mineral of Utah, copper (Cu) is a soft metal that has been mined for centuries and used in all kinds of industry. Pure mineral specimens of copper are rarely found as nuggets. Branching forms are the most common crystal habit. It is one of the easiest to identify by color and is found in the US, Australia, Russia, and Germany.
Known as the hardest substance on earth, the diamond(C) has an octahedral or dodecahedral crystal formation or rarely a cubic one. Only 20% of diamonds are used by the jewelry market. The rest are used in industry such as electronics, optics, and thermal insulation. There are diamond mines all over the world and low quality mineral specimens are relatively easy to purchase.
Used primarily for jewelry, turquoise [CuAI6 (PO4)4(OH) 8*5(H2O)] has been mined for centuries and is found in the Middle East and United States. The rarity of turquoise with its triclinic crystal system combined with its popularity has provoked the use of the mineral chrysocolla [CuSiO3-nH2O] as its imitation. Obtaining mineral specimens of each would provide opportunity for comparison.