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Quartz Crystal, Types of Quartz, Properties and Photos

four terminated quartz crystals
Contents

1. Quartz Meaning and Properties
2. What Does Quartz Do? 
3. Quartz Piezoelectric Crystal
4. Types of Quartz
5. Article Pictures
6. Shop for Quartz

Quartz Crystal Meaning and Properties

Quartz is the most common mineral in Earth's crust after ice and feldspar.  It can be found in almost every geological environment and is a component of virtually every rock type.  It has exceptional durability and is the main constituent in all types of sand.

Quartz is the world's most diverse mineral in terms of varieties, colours and forms because of its abundance and widespread distribution.  It can be found in sedimentary rocks as grains of sand and as crystals in igneous and metamorphic rocks.  Quartzite which is composed almost completely of the mineral quartz is produced through the metamorphism of sandstone.

Silicon dioxide is a chemical compound of two of the most abundant elements in Earth's crust, silicon and oxygen.  Found most commonly in nature as the mineral quartz, it exists in several crystalline forms and a number of cryptocrystalline forms.  Silicon dioxide is also known as silica

The name quartz comes from the old German word 'quarz' which first appeared in 1530.  In Ancient Greece the mineral quartz was known as 'krustallos' from 'kruos' meaning 'icy cold'.  This is possibly because of the clarity of some quartz crystals.

Theophrastus Ancient Greek philosopher and successor to Aristotle believed colourless quartz crystals were a unique type of ice that wouldn't melt. 

cluster of mainly upright translucent quartz crystals

What Does Quartz Do?

The term rock crystal can be used to describe the purest type of quartz.

Quartz occurs in two forms, crystalline which is often abbreviated to crystal and cryptocrystalline which means crystals are too small to be seen with the naked eye.

Crystal quartz (or quartz crystal) is colourless and transparent hence the term 'crystal clear'.  It can also occur in many different colours from milky white to dark brown verging on black.  Many different varieties of quartz exist.  Coloured varieties tend to be translucent as opposed to transparent and most have their own name.

Inclusions in quartz are relatively common.  This material is often referred to as included quartz. Rutile and tourmaline are two of the most common mineral inclusions in quartz. 

The optical properties of quartz led to its extensive use in lenses and prisms.  It was once widely used in electronic components although has now been replaced with a synthetic alternative.

As well as its electrical properties quartz is also resistant to heat.  Being graded 7 on Mohs scale of mineral hardness makes it harder than many other natural minerals.  It's therefore often used as an abrasive.  Despite being hard it's also brittle so will break or shatter easily. 

Hardness and toughness are not the same.  Hardness refers to a mineral's resistance to being scratched by another.  Toughness correctly known as tenacity refers to a mineral's resistance to being bent, cracked, chipped or broken.

Quartz Piezoelectric Crystal

Quartz is a piezoelectric (pee-ay-zo-electric) crystal meaning it releases an electrical current when squeezed, compressed or distorted.  When the process is reversed and the crystal is exposed to an electrical current, it releases a vibration at a precise frequency.  Other crystals that are piezoelectric include topaz and tourmaline.  Sugar cane, DNA, bone and even silk are also piezoelectric.

Piezoelectricity was discovered by French brothers Jacques and Pierre Curie in 1880.

Quartz was the first crystal to be used in a radio transmission and was fundamental to the development of computers.  For a quartz crystal to vibrate it must be exposed to mechanical stress.  The stress may come from it being squeezed, compressed or distorted.  Quartz crystals vibrate at precisely 32,768 times a second.  The vibration is similar to the way a glass rings when tapped.two colourless transparent quartz crystals surrounded by the mineral sodaliteThe word 'piezoelectric' comes from the Greek 'piezein' meaning 'squeeze' or 'press'.  Today piezoelectricity is used everywhere around the world in countless products.  Some of these include time keeping devices, radios, televisions, video equipment, sensors and mobile 'phones.

As technology advances the future of piezoelectricity is endless.  In some train stations in Japan the vibration of footsteps is being used to create the energy that powers ticket gates and displays.

Types of Quartz

Agate
Translucent variety of chalcedony known for its distinctive banding

Amethyst
Purple variety of quartz whose colour is caused primarily by iron but also manganese

Aventurine
Type of translucent quartz usually identified by its platy inclusions

Bloodstone
Dark green chalcedony, often features red markings from inclusions of hematite

Carnelian
Reddish to rich orange coloured quartz.  Translucent variety of chalcedony.  Sometimes referred to as cornelian

Chalcedony
Variety of microcrystalline quartz, white in its purest form.  Most types of chalcedony have their own unique name such as agate bloodstone or carnelian

Chevron Amethyst
Combination of colourless or milky white quartz combined with amethyst.  Named for its chevron-like markings.  Tends to be known as banded amethyst in the UK 

Chrysoprase
Translucent apple green variety of chalcedony. The colour comes from nickel

Citrine
Yellow to yellowish brown coloured quartz that's fairly rare.  Most commercial grade citrine is heated amethyst

Included Quartz
Inclusions are common in quartz and although some varieties have their own name, most are known as included quartz.  Tourmalinated and rutilated quartz are probably the best known varieties

Jasper
Cryptocrystalline variety of chalcedony. Features fine inclusions of varying amounts of other minerals and substances. These cause the stone to be opaque and are responsible for its colour

Milky Quartz
White to greyish-white translucent to opaque variety.  Often occurs in the same deposit as rock crystal

Onyx
Striped variety of agate with alternating black and white bands. The name is widely used incorrectly

Rose Quartz
Pink coloured stone usually translucent. Crystal habit is massive.  Pink quartz which is considered to be a different variety is often confused for rose quartz.  The main difference is crystals are quite common whereas in rose quartz they have never been found

Rock Crystal
Colourless and transparent, its name came about during the late Middle Ages to differentiate it from a newly produced colourless material known as glass.  At that time glass was known as crystal or crystal glass
tumbled quartz crystalsSard
Translucent light to dark brown coloured chalcedony.  Until the Middle Ages sard shared its name with carnelian.  Gemstones with bands of white sard and chalcedony are called are called sardonyx

Smoky Quartz
Translucent to transparent mineral that occurs in various shades of brown.  Colour can vary from light to so dark it almost appears to be black.  Sometimes incorrectly referred to as smoky topaz which is a completely different mineral

Tigers Eye
Type of quartz with a rich golden yellow colour caused by the presence of iron.  Also known as tiger eye

Article Pictures

The quartz cluster in the second picture in our article is courtesy of Stan Celestian.  The next picture features quartz and sodalite from our collection.  The clear quartz tumbled stones are also from our collection.  All three pictures are clickable and redirect to the original full size image.

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