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Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Main. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it.

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  1. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Main

  2. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Top left Quartz Quartz is a crystal form of silicon dioxide (Si02), and grows in a 6-sided prism ending in a 6-sided pyramid. Smoky quartz The colour of smoky quartz is thought to come from either iron impurities, titanium impurities or irradiation. It’s relatively common.

  3. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Top mid Quartz Quartz is a crystal form of silicon dioxide (Si02), and grows in a 6-sided prism ending in a 6-sided pyramid. Citrine The colour of citrine is thought to come from iron impurities or irradiation. Relatively rare in its natural form, it’s more common for a citrine to actually be a heat-treated amethyst.

  4. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Top right Quartz Quartz is a crystal form of silicon dioxide (Si02), and grows in a 6-sided prism ending in a 6-sided pyramid. Amethyst The colour of amethyst is thought to come from iron impurities or irradiation. This deep violet colour is quite rare.

  5. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Center left Garnet Garnets are a group of minerals varying in the general formula X3Y2(SiO4)3. The crystal structure is usually dodecahedral (12-faced) although it can also be cubic (6-faced). Pyrope (“Red Garnet”) Pyrope is a magnesium-aluminium silicate - Mg3Al2(SiO4)3. It is formed in high-pressure rocks.

  6. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Center mid Garnet Garnets are a group of minerals varying in the general formula X3Y2(SiO4)3. The crystal structure is usually dodecahedral (12-faced) although it can also be cubic (6-faced). Rhodolite Rhodolite is a variety of Pyrope with a “rosy” colour. It can easily be mistaken for the more valuable Pink Tourmaline.

  7. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Center right Garnet Garnets are a group of minerals varying in the general formula X3Y2(SiO4)3. The crystal structure is usually dodecahedral (12-faced) although it can also be cubic (6-faced). Spessartite Spessartite is a manganese aluminium garnet - Mn3Al2(SiO4)3. It was first found in Spessart, Germany. There are only a few places in the world where this gem occurs.

  8. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Bottom left Tourmaline The group of minerals called tourmalines some of the most chemically complicated silicates. The constituent elements vary to give a wide variety of colours. Blue-green As with many types of tourmaline, blue-green tourmaline is dichroic – depending on the viewing angle, it appears either blue or green. The colour is thought to be due to traces of chromium and copper.

  9. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Bottom mid Tourmaline The group of minerals called tourmalines some of the most chemically complicated silicates. The constituent elements vary to give a wide variety of colours. Yellow The colour of yellow tourmaline is thought to be due to traces of magnesium. It is found in Malawi and Zambia.

  10. Semi-precious gems Here are a few semi-precious gems from the quartz, garnet and tourmaline families. Click a stone to find out more about it. Bottom right Tourmaline The group of minerals called tourmalines some of the most chemically complicated silicates. The constituent elements vary to give a wide variety of colours. Pink Pink tourmaline is a variety of Rubellite (deep red) which in turn is a variety of Elbaite- Na(Li1.5,Al1.5)Al6Si6O18(BO3)3(OH)4.

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