ANDALUSITE ROUGH PARCEL 163.20 CTS [F814]

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About This Auction		About This Seller: QUALITY ROUGH
Minimum Bid (USD)		Feedback Rating	99.57% Positive
Current Bid (USD)	0.00	Member Since	13 Jul 2009 in Australia
Bid Increment (USD)	1.00	View feedback Send seller message View 1706 other auctions from this seller More about this seller
Bids Placed	0
Starting Bid (USD)	16.00
Reserve Price (USD)	none
Starts	March 13, 2010 2:05 AM
Ends	March 15, 2010 3:00 AM	Basic Shipping Information
Auction Category	Andalusite	Shipping Cost	3.00 paid by buyer
Auction ID	124652	Shipping Insurance (optional)	7.00
Ends in 8 hours
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Description

SEDAGEMS IS COMMITED TO A FULL DISCLOSURE OF STONES WITH A MONEY BACK GUARANTEE

ANDALUSITE ROUGH

This is a a parcel of natural untreated rough parcel ready to cut.

Faceted andalusite stones give a play of red, green, and yellow colors that resembles a muted form of iridescence, although the colors are actually the result of unusually strong pleochroism

Weight 163.20 cts app

Size of largest piece 15 x 11 x 8 mm app

Andalusite is pleochroic, i.e. it shows different colours in different directions. When cutting most pleochroic gemstones, such as iolite and tanzanite, the trick is to minimise the pleochroism and maximise the single best colour. With andalusite the opposite applies: cutters try to orient the gem to get a pleasing mix of colours: orange-brown and a yellowish green or gold.

When they succeed, andalusite looks quite unlike any other gemstone, with patterns of colour dancing around the facets. The best colour play is seen in fancy shapes, particularly rectangular cushion shapes: in round cuts, the colours blend together.

Andalusite is mined in Brazil and Sri Lanka.

In the past andalusite was sometimes called "poor man's alexandrite" because it offers colour play at a low price, but in fact it does not actually bear much resemblance to alexandrite, which changes from green to red in different light. In fact it is not really a colour-change stone at all because the colours are present at the same time.

Andalusite is a common metorphic regional mineral which forms under low pressure and moderate to high temperatures. Called Lapis Crucifer in ancient texts. The minerals kyanite and sillimanite are polymorphs of andalusite, each occurring under different temperature-pressure regimes and are therefore rarely found together in the same rock. Because of this the three minerals are a useful tool to help identify the pressure-temperature paths of the host rock in which they are found.