What Is a Quartz Crystal?

Quartz is a silicate mineral with many colors that is piezoelectric, producing electric voltage when compressed in certain directions. Due to this characteristic, it has found use in clocks and radio systems.

Crystals can vibrate in different ways and each has a resonant frequency which depends on its load capacitance.

Stability

Stability refers to the ability to maintain the same resonant frequency over a wide temperature range, an essential quality for quartz crystals that need to produce output frequencies with consistent timing and frequency stability. Oscillators with built-in temperature compensation mechanisms such as TCXOs or OCXOs can significantly enhance frequency stability performance and are an invaluable way to guarantee frequency accuracy and precision.

Quartz is an abundant mineral found throughout rock strata through which silica-rich water has seeped, as well as in metamorphosed banded iron formations. Silica dioxide forms the core component of pure quartz; however, impurities add variety both in terms of color and properties.

Tiger’s eye, or golden to reddish-brown cryptocrystalline quartz with silky, chatoyant sheen, results from pseudomorphic replacement of crocidolite with silica (blue asbestos). Chrysoprase is an apple-green microcrystalline form of quartz associated with nickel ore deposits and often forms fillings for fractures, veins or nodules in serpentinite or lateritic nickel ores.

Transparency

Quartz crystal is known for its flawless arrangement of silicon and oxygen atoms, making it suitable for gems and crystal tools. Unfortunately, impurities like mineral deposits or fractures can hinder its transparency, rendering this precious mineral unsuitable for these uses.

Calcite can resemble quartz in appearance but differs by being harder and lacking any cleavage lines. Agates and chalcedonies, both variants of quartz, also produce an iridescence while black onyx owes its even black hue to ancient dyeing practices.

Rutilated quartz is an uncommon rock crystal variety characterized by golden needles of rutile arranged in various patterns within its transparent stone, known as Venus hairs. These special inclusions indicate its chiral structure and distinguish it into its respective sub-varieties of A and B Quartz varieties.

Clear quartz crystals have long been associated with healing and metaphysical practices. According to crystal therapy, clear quartz stores information and energy, amplifies thoughts and intentions, and helps clear the mind.

Conductivity

As is true of other crystals, quartz displays an optical property known as birefringence. If you hold up a clear calcite rhombohedron over newspaper text, a double image of letters appears due to light passing through and being split into two rays with different polarizations.

Quartz displays this polarization difference due to its crystal structure (called symmetry). Many minerals show anisotropy; that is, they respond differently depending on which direction an external force is applied.

Quartz crystals expand more slowly when expanded perpendicularly than parallel to the C-plane, so when extracting crystals from vugs or pockets you need to be mindful that their crystals may break off unexpectedly – this phenomenon is known as direction of cleavage.

Pitch

Quartz is one of the most abundant minerals on Earth. With an average hardness rating of 7, it features vitreous to glossy luster. When pure, its colorless qualities may be altered by impurities in citrine (gold), white chalcedony milky quartz (white chalcedony milky quartz), pink rose quartz, purple amethyst or red bloodstone, heliotrope or carnelian (bloodstone, heliotrope or carnelian) or gray/brown (smoky quartz).

Quartz crystals also exhibit piezoelectricity, the ability to generate electric voltage by applying mechanical stress along their crystal axes. This can be utilized in quartz oscillators such as those found in watches, computers and cell phones in order to ensure accurate timing functions and frequency regulation.

Quartz forms when silica rich magma solidifies, producing silica-rich rocks which then cool. Quartz frequently occurs with other minerals in these igneous rocks such as potassium feldspars, biotite and muscovite; in sedimentary rocks it often appears with calcite, dolomite and various clay minerals.