Quartz is not a native element. This ubiquitous substance constitutes about 12% of the Earth’s lithosphere and is one of the most common minerals found in igneous, metamorphic, and sedimentary rocks. Understanding why quartz does not fit the description requires a clear look at the specific chemical definition of a native element in mineralogy.
Defining Native Elements
A native element is a mineral that occurs in nature in an uncombined or pure state, meaning it is composed of atoms of only one element. This classification is reserved for elements that can form a distinct mineral structure without chemically bonding with other elements.
Native element minerals are traditionally categorized into metals, semimetals, and nonmetals. Examples of native metals include gold (Au), silver (Ag), and copper (Cu). Nonmetal examples include carbon, which forms both diamond and graphite, and sulfur (S), often found near volcanic vents and hot springs.
The Chemical Composition of Quartz
Quartz is a compound, not a single element. The substance is chemically known as silicon dioxide (SiO2). This formula indicates that quartz is composed of two distinct elements, silicon (Si) and oxygen (O), which are chemically bonded together.
The fundamental structural unit of quartz is the silicon-oxygen tetrahedron, where a single silicon atom is situated at the center, surrounded by four oxygen atoms. In the quartz crystal lattice, each oxygen atom is shared between two adjacent silicon-oxygen tetrahedra. The strong covalent bonds within this structure are responsible for quartz’s characteristic hardness of 7 on the Mohs scale.
Placing Quartz in the Mineral Kingdom
Quartz is not grouped with native elements but is instead classified into the Silicates. Mineral classification systems, such as the Dana and Strunz systems, place quartz within the Silicates, which are minerals whose structures are based on the silicon-oxygen tetrahedron. Silicate minerals make up over 90% of the Earth’s crust.
More specifically, quartz is designated as a tectosilicate, or framework silicate. Tectosilicates are defined by the three-dimensional interlocking pattern of their silicon-oxygen tetrahedra, which creates an extremely strong and resilient structure. Furthermore, because its chemical formula is SiO2, quartz is also classified chemically as an oxide mineral, a grouping separate from the true native elements.