Families of Crystals and Gemstones

Crystals can be divided into groups that have important material properties in common. There are also many examples of families within families, e.g. red jasper is a form of jasper, which is a form of chalcedony, which is a form of quartz.

Here is a simple introduction to some of the most well-known types of crystals. Most of the crystals mentioned here are also described in more detail elsewhere on this website. See the links below.

Family Name	General Information	Members of Family	Typical Uses	Photographs
Quartz	Quartz is a very common type of crystal that exists in a wide variety of colours, forms and specific chemical compositions. Its overall chemical formula is SiO₂ (i.e. it is mainly silicon dioxide). The different varieties of quartz exist due to the presence within the overall SiO₂ structure of other chemical elements, and how those other elements are arranged within the structure.	Amethyst - exists in various shades of purple due to the presence of the element manganese (Mn) in the quartz.	Meditation, connection with one's spirituality, cleaning/cleansing other crystals after use.
		Chalcedony - There are many forms of Chalcedony. See the seperate section (below)
		Citrine - aged (faded) amethyst may be mistaken for citrine.	Associated with the attainment and maintenance of wealth. Sometimes carried in purses or kept in cash tills for good financial luck.
		Clear Quartz - silicon dioxide without the presence of inclusions or other elements
		Rose Quartz - silicon dioxide (quartz) in the presence of the element titanium (Ti), which gives rise to the pink colour of Rose Quartz.
		Smoky Quartz
Aventurine	Aventurine is formed when bright particles such as mica and/or hematite (or similar) are distributed within a mineral such as quartz (silicon dioxide) or feldspar (also known as flourite). It is possible to see many tiny particles within samples e.g. tumble stones of aventurine	Green Aventurine - the most common colour of aventurine, this exists in a wide range of shades of green - from pale through to dark.	Used to re-balance and optimize the heart chakra
Aventurine		Red Aventurine - colours range from dark pink to cherry pink/red.
Chalcedony	Chalcedony is a naturally occurring solid aggregate form of silicon dioxide (SiO₂) that consists of fine intergrowths of the minerals quartz and moganite. It has sometimes been classified as a member of the quartz family due to its SiO₂ content. However, while quartz alone has a trigonal structure, chalcedony also includes moganite, which has a monoclinic crystal structure. The word 'chalcedony' itself is usually only used to refer to white or pale coloured examples of this type of rock. However, as a general term it also includes many other colours of rocks that are generally known by other more specific names. Some of the most common examples are included here.	Agate - tends to have fine grains and is found in many bright colours.	Hardstone carvings incl. to make ornaments and in architecture.
		Bloodstone (also known as heliotrope) - green with red or yellow spots, typically green chacedony with red inclusions of iron oxide or red jasper.	One of the traditional birthstones for the month of March.
		Carnelian - a red-brown form of chalcedony, the reddish colour being due to the presence in its structure of particles of iron oxide. Similar to the darker and harder mineral, sard (a term sometimes used interchangeably with 'carnelian').	Used by the Minoans (Crete, 2700-1500 BC) to make jewellery and by the ancient Romans to made seals to identify documents, some such seals being mounted on signet rings.
		Jasper - exists in many different compositions and hence colours. See 'Jasper Family', below.
		Onyx
Jasper	Jasper is an opaque (i.e. solid in the sense that it does not transmit light) form of chalcedony, which exists in many different colours many of which also incorporate attractive patterns.	Green Jasper	Heart Chakra
		Red Jasper	Base/Root Chakra
		Yellow Jasper - sometimes also known as Bruneau Jasper
Tigers Eye		Blue Tigers Eye - a relatively unusual form of the gemstone tigers eye in which the stone reflects a range of shades of blue up to very dark blue.
		Golden Tigers Eye (also called Gold Tigers Eye) - is the most common and well-known form of Tigers Eye.
		Red Tigers Eye - a relatively unusual form of the gemstone tigers eye in which the stone reflects a range of shades of red up to very dark red.

Quartz

Quartz is the most common type of crystal and is predominately silicon dioxide. However, quartz exists in very many different forms depending on the other elements present.

Amethyst exists in various shades of purple due to the presence of the element manganese (Mn) in the quartz.

Uses / associations:
Meditation, connection with one's spirituality, cleaning/cleansing other crystals after use.

Chalcedony
There are many forms of Chalcedony.
See seperate section (below the 'Quartz family').

Citrine
Aged (faded) amethyst is sometimes mistaken for citrine.

Uses / associations:
Citrine is associated with the attainment and maintenance of wealth. Sometimes carried in purses or kept in cash tills for good financial luck.

Clear Quartz
A simple description of the chemical composition of clear quartz is that it is silicon dioxide without the presence of inclusions or other elements (that often result in the colours of other forms of quartz).

Rose Quartz
Chemically, rose quartz is silicon dioxide (quartz) in the presence of the element titanium (Ti), which gives rise to the pink colour of rose quartz.

Aventurine

Aventurine is formed when bright particles such as mica and/or hematite or similar are distributed within a mineral such as quartz (silicon dioxide) or feldspar (also known as flourite). It is possible to see many tiny particles within samples e.g. inside tumble stones of aventurine.

Green Aventurine is the most common colour of aventurine. It exists in a wide range of shades of green, from pale green through to dark green.

Uses / associations:
One of several crystals that is sometimes used to re-balance the heart chakra.

Red Aventurine is found in colours that range from dark pink to cherry pink / red.

Chalcedony

Chalcedony is normally classified as a member of the quartz family. It includes many types of crystals of which those listed opposite are only the most common examples.

Agate
There are many forms of agate, including e.g. blue lace agate (pictured, right)

Bloodstone

Carnelian

Jasper exists in many different compositions and hence colours. See more about the 'jasper family' in the following section (below).

Onyx
Typically black in colour

Jasper

Jasper is an opaque (i.e. solid in the sense that it does not transmit light) form of chalcedony, which exists in many different colours many of which also incorporate attractive patterns.

Green Jasper

Uses / associations: The heart chakra

Red Jasper

Uses / associations: The base / 'root' chakra

Yellow Jasper is sometimes also known as Bruneau Jasper.

Tigers Eye

There are several forms of tigers eye. They are distinguished by the overall colour of the stone, which is most obvious after polishing e.g. when looking at tigers eye tumble stones.