Gemology: Gemstones beginning with X, Y and Z...

We have reached the final stop in our gemology journey, with a look at gemstones beginning with X, Y and Z.

Xanthite

Xanthite is a form of Vesuvianite, but where Vesuvianite is named for Mt Vesuvius in Italy, Xanthite is found near New York in the United States. Whilst both are a green crystalline gem, xanthite contains more of the mineral manganese.

Image credit: Linnell [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)

Gemstones beginning with Y? We couldn't find any, other than "yellow" variants of other gems!

Zebra Stone

Zebra Stone is a sedimentary rock found only in the East Kimberley region of Western Australia, characterised by its layered stripes of brown and white (creamy beige), or black and white. Also known as Zebra Rock or Zebra Jasper, it's a lovely decorative stone for ornamental or costume jewellery use. Discovered in 1924, all Zebra Stone has been estimated to be around 600 million years old, though scientists and geologists have yet to determine how it was formed.

Image credit: By Matt Brann, via http://www.abc.net.au/site-archive/rural/content/2011/s3279298.htm

Zircon

Zircon is a transparent gemstone naturally occurring in many colours. Clear zircons were long thought to be diamonds until reliable testing was developed to tell the difference, and clear zircon remains a common diamond alternative in jewellery use. Natural zircon can be found in shades of yellow, green, red, brown and blue. The more golden tones are the most commonly occurring, while blues, greens and reds are the rarest and most valuable. It is thought that zircon got its name from its golden hued stones; "Zar Gun" being the old Persian term for gold coloured.

The confusion between clear zircon and diamond is easy to understand. Zircon can have within it the same 'fire' emitting flashes of colour. It's also incredibly tough. In fact, three zircon gemstones found in Jack Hills, Australia, have been scientifically proven to be the oldest minerals ever discovered on earth. The three zircons were all tested to be around 4.375 BILLION years old!

Zoisite Zoisite is the family name of a group of minerals including the gemstone Tanzanite. The name is rarely used to describe a gemstone in its own right, but if you find zoisite in a store it will most likely be an opaque multi-coloured semi-precious gem in shades of blue, red, green pink and purple.