How Is Natural Quartz Made?

Prerequisites for The Formation of Natural Quartz

• Quartz requires both high temperature and high pressure to form in the natural environment. For instance, macrocrystalline quartz will not form in regions where temperatures drop below 100 degrees centigrade, while cryptocrystalline quartz will only form between 150 and 200 degrees centigrade. The formation of cyrptocrystalline quartz can also be inhibited by the absence of liquid water.

Formation in Water Solutions

• Natural quartz crystals can form in hot hydrothermal environments. In these areas, they are made under intense heats between 100 and 400 degrees centigrade and very high pressures. The quartz grows by the addition of dissolved orthosilic acid at the surface of the water. The solution in which they are formed also contains a high amount of ions, as well as carbon dioxide. If temperature and pressure drop, then quartz formation may slow or even halt. As the crystals enclose drops of the encompassing water when they form, they can be used to reconstruct environmental conditions.

Formation in Igneous Rocks

• Quartz can also form in igneous rocks. While the ambient conditions are different, the formation of natural quartz crystals is similar to in watery solutions. When magma intrudes over other rocks and does not erupt onto the Earth's surface, but stays inside the crust, it cools more slowly than if it erupted by volcanic eruption. During the gradual cooling, crystals of different minerals will appear in the order determined by the magma's chemical composition. In granite, for instance, mica forms first, followed by feldspar, and finally quartz. As such, ideal-shaped quartz crystals are rarely found in granite.

Formation of Shocked Quartz

• Shocked quartz forms when a surface is subjected to a sudden very high pressure. Shocked quartz is distinct in possessing shocked laminae, which are small parallel lines that crisscross other parallel lines on the quartz surface that are planar features exhibiting only slight deformation. Shocked quartz can be found in the craters created by the detonation of atomic weapons, as well as meteor impact craters. In impact craters, the pre-existing minerals are often alternated by the powerful meteoric impact.