What is Quartz?
In the most basic sense, quartz is the crystalline form of silicon dioxide. When quartz grows into large crystals, lapidaries can cut varieties such as rock crystal, smoky quartz, amethyst, or citrine. Quartz can also grow into stones made of tiny microcrystals. In this case, lapidaries can cut chalcedonies, like agate or jasper.
How Does Quartz Form?
Most quartz forms in either igneous rocks or environments with geothermal waters.
In igneous rocks, quartz forms as magma cools. Like water turning into ice, silicon dioxide will crystallize as it cools. Slow cooling generally allows the crystals to grow larger.
Quartz that grows from silica-rich water forms in a similar way. Silicon dioxide dissolves in water, like sugar in tea, but only at high temperature and pressure. Then, when the temperature or pressure drops, the solution becomes saturated, so quartz crystals form.
How Does Smoky Quartz Form?
Quartz gets smoky brown shades when the rocks around it contain radioactive elements. Over time, the radiation alters the crystal, causing defects…