Quartz

-Mineral Name: Quartz

-Chemical Composition: SiO2 (Silicon Dioxide)

-Color: Red, Blue, Yellow, Orange, Green, Gray, Black, Brown, Pink, Purple, White, and colorless. Sometimes quartz can show many colors or even be banded (4).

-Streak: White/Clear

-Hardness: 7

-Cleavage/Fracture: Quartz fractures through the method of conchoidal fracture, meaning that it breaks into a circular/spherical pattern.

-Crystal Form: If Quartz is given plenty of room to grow, its crystal form will be hexagonal. It is also common to find mineral twinning among quartz samples. This means that two separate crystals share portions of the same crystal lattice, forming a “twin” crystal structure (3).

-Luster: Vitreous

-Special Features: Comes in many different colors due to impurities in the crystalline lattice. Also, its hardness and fracture set it apart.

Varieties: Amethyst, Tourmalinated Quartz, Aqua Aura, Star Quartz, Aventurine, Smoky Quartz, Blue Quartz, Scepter Quartz, Cactus Quartz, Rutilated Quartz, Chalcedony, Rose Quartz, Citrine, Rock Crystal, Faden Quartz, Ferruginous Quartz, Herkimer Diamond, Milky Quartz, Morion, Phantom Quartz, Prase, Praseme, Prasiolite, Rainbow Quartz (4).

-Mineral Group: Quartz belongs in the mineral group Silicates. It is composed of silica and and oxygen. The silicate mineral group is divided into 6 subsections. The section that quartz is in is tectosilicates. Tectosilicates share all oxygen atoms to create a three-dimensional structure. It has a 1:2 ratio Silica to Oxygen (4).

-Environment: Quartz is one of the most common minerals. The majority of quartz forms in magma. If given space and the right growing conditions, quartz will form hexagonal crystals.

Associated Rock types: Quartz is found in all three rock types, igneous, metamorphic, and sedimentary rocks. Some examples are granite, aplite, pegmatite, pumice, rhyolite, tuff, sandstone, hornfels, quartzite, and novaculite.

-Occurrence in North America: Quartz can be found anywhere in North America. One notable location is in Herkimer County, where the “Herkimer diamond” is found. But don’t let its name fool you. This diamond is no diamond, it is a double-terminated quartz crystal, meaning it has double pointed ends and is not attached to a rock face (free floating). These crystals can be found in many places, but only the ones found in Herkimer County get the name (1).

-Economic Uses: The largest economic value for quartz is in its gemstones. These gemstones are often cut to reveal it’s inner beauty and used in making jewelry and other decorative features. Some examples of these gemstones are smoky quartz, rose quartz, citrine, amethyst, rock crystal, and ametrine. Some of the most expensive and rarest gemstones are painite, musgravite, jadeite, and alexandrite whose prices range between $12,000 - $60,000 per carat (2).

-Industrial Uses: Quartz is used in the glassmaking industry. Quartz-rich deposits of sand are used to create glass because silicate-rich minerals are great for creating glass (8). Quartz is used with processing piezoelectricity because of its molecular structure. It works by applying mechanical stress to quartz which causes the molecular structure become polarized. This polarization allows for a current of electricity to travel through it, thus transforming mechanical energy into electricity (6).

First Notable Identification: The earliest name for quartz was κρύσταλλος or kristallos, established by Theophrastus around the years 300-325 BCE (10). The root words for this phrase are “κρύοσ”, meaning ice cold, and “στέλλειυ”, meaning to solidify. This suggests that ancient peoples believed that quartz was permanently solidified ice. But it wasn’t until the year 1505 that the earliest use of “querz” was published anonymously, leading to the current name of quartz (10).

-How We Identified It: Quartz is a hard mineral to identify. You can start by looking at, fracture, hardness, and crystal form. Trying to use color when trying to identify quartz is the worst because it comes in so many colors.

-Don’t Confuse It With: Don’t confuse this mineral with other clear minerals such as calcite, halite, and barite. The easiest way to differentiate these minerals from quartz is with its hardness. Quartz is a 7 on the Moh’s hardness scale compared to calcite (3), halite (2-2.5), and barite (3-3.5).