Biotite. This mica mineral forms shiny, flexible flakes that are deep black or brownish-black in color. Large book crystals occur in pegmatites and it is widespread in other igneous and metamorphic rocks, while tiny detrital flakes may be found in dark sandstones.

igneous rocks
Mica minerals make some rocks sparkle! They are often found in igneous rocks such as granite and metamorphic rocks such as schist. They sparkle because light is reflected on their flat surfaces, which are where the mineral breaks along its plane of cleavage.

Common rock crystals found in Tennessee include quartz, pyrite sphalerite, galena, fluorite, calcite, gypsum, barite and celestite.

Obsidian Although obsidian has a shiny black surface, the stone is not automatically crystalline. It may be formed as a result of various materials subjected to volcanic activity.

If the rock feels lighter than that surrounding rocks, it may be a geode. Geodes have a hollow space inside, which is what allows the crystals to form. You can also shake the rock next to your ear to test whether it is hollow. You may hear small pieces of rock or crystal rattling around inside if it is hollow.

Environment

The best places to dig for gems in Tennessee are the public gem mines, such as Cooper’s Gem Mine, and Little River Gem Mine, among others. The Tennessee River and its tributaries are great for finding freshwater pearls. In contrast, the Cumberland Plateau is filled with gemstone specimens.

Cooper’s Gem Mine For a small entrance fee, young miners and aspiring geologists can come to this mining facility to dig up mine ore. Along with multi-colored quartz, you may find a number of emeralds, garnets, and other gemstones and minerals in this mine site.

The black onyx is more valuable than the other colors of onyx available, too. Black onyx can vary in value from $1 to $500 per carat on its own. That varies with the setting of the gemstone itself. With a setting of silver, it’ll be less than a setting of yellow or white gold.

The black color is caused by impurities, mainly by iron oxide. Although their color typically darkens with extended sunlight exposure, it could also turn these stones dull.

These black diamonds are also called carbonado, which means black rock. The reason for their black color are the impurities that came with them. Clear diamonds are expensive as they are precious gemstones.

Igneous rocks such as granite or lava are tough, frozen melts with little texture or layering. Rocks like these contain mostly black, white and/or gray minerals.

Different Types of Shiny Black Rock. Black rocks can be easily found in various places, including mountains and coastlines. However, a shiny black rock may not be that common. These types of rocks could be valuable gemstones or minerals that could be used for jewelries or they could also be made into a collection.