Quartz Species Part 1 Rock Crystal and Smoky Quartz

Hi everyone,

Today I would like to discuss the quartz family.  There are many parts to the quartz family so this will also be a multi-part series.  I hope it is easier for everyone if I group the different types of quartz and talk about them separately.  I, myself find it easier to discuss the various groups if they are broken up into smaller sections.  This also allows for the material to be absorbed better.  As before all the information that I am writing about is found in the book Gemstones of the World by Walter Schumann.

The word quartz is derived from the Slavic word for hard.  It is the name for a group of minerals that have the same chemical composition.  The Macrocrystalline quartz are crystals recognizable with the naked eye.  This type of quartz has the gemstones amethyst, aventurine, rock crystal, blue quartz, citrine, hawk's eye, prasiolite, quartz cat's eye, smoky quartz, rose quartz and tiger's eye.  Cryptocrystalline quartz are microscopically small crystals.  The gemstones included in this type of quartz typically known as chalcedony are: agate, petrified wood, chrysoprase, bloodstone, jasper, carnelian, moss agate and sard.

Rock crystal is a colourless stone, the colour streak is white and the density is 2.65.  The Mohs hardness is 7 and there is no cleavage. The crystal system is trigonal, hexagonal prisms.  The chemical composition is silicon dioxide and the transparency is transparent.  The name comes from the Greek meaning ice.  Cuttable rock crystal material is rare.  This gemstone can be found in Brazil, Madagascar, the United States and the Alps.  This stone is used primarily for costume jewellery and bowls and vases.

Smoky quartz is named after the smoky colour.  The very dark stones are called morion and caingorm.  The colour is brown to black, smoky grey.  The colour streak is white and the density is 2.65.  The Mohs hardness is 7 and there is no cleavage.  The crystal system is trigonal, hexagonal prisms.  The chemical composition is silicon dioxide and the transparency is transparent.  The name smoky topaz is no longer recognized in the trade to describe smoky quartz.  There are frequent inclusions of rutile needles in smoky quartz.  This gemstone can be found in Brazil, Madagascar, Russia, Scotland, Switzerland and the Ukraine.  It uses are the same as for rock crystal.

I hope everyone learned something new and exciting about rock crystal and smoky quartz.  I know that I did and I hope everyone had fun learning.  I am really enjoying writing this blog about gemstones.  I find that I am learning something new everyday and that is what is making this so rewarding for me.  I hope that you will drop me a line and let me know how I am doing. I would love to hear from you.  Until next time.

The rare gem lady