Crystal formation and structural differences

Crystals form naturally in the Earth’s crust when magma travelling upwards from the core starts to cool down. This process of crystal formation can take billions of years and is known as crystallization. Differences in temperature, pressure and chemical composition are all factors that influence the type of crystal that forms. Impurities can also affect a crystal’s chemical make-up and colour. For example, quartz crystals are naturally clear, yet the presence of iron or manganese compounds add a vibrant purple or pink colour, creating variations known, as amethyst and rose quartz.

Minerals, Rocks, Crystals and Gemstones

The terms mineral, rock, crystal and gemstone are often used interchangeably, however each one indicates significant structural differences.

MINERAL

A mineral is a naturally occurring solid substance that contains distinct crystalline structure and chemical composition. While not all minerals are visible crystals, they do contain crystals in microscopic form. There are more than four thousand identified minerals, each with is own characteristics: it must be naturally occurring, inorganic (though there are some exceptions, such as coal), it must be a solid at room temperature, have a definite chemical composition and an ordered internal structure. Each of these characteristics must be present for a substance to be identified as a mineral.

ROCK

Rock is composed of several minerals combined, and does not contain the specific chemical composition that would normally be found in a mineral. Rocks can also include other organic remains, as well as mineraloids – substances similar to minerals that do not demonstrate crystallinity.

CRYSTAL

Most minerals occur naturally as crystals. A crystal is a solid material made up of ions, atoms and molecules arranged in a orderly repeating pattern. Crystal structure can influence the physical properties of a mineral, including its colour, lustre, texture and form.

GEMSTONE

A gemstone is a valuable mineral or crystal that has been cut and polished, often to use in jewellery and other adornments. The value of a gemstone depends on quality, size, rarity and colour.