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www.mineralgallery.co.za Minerals K-O |
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Mimetite |
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Name
Mimetite
Chemistry
Pb5{CI(AsO4)3}
Uses
As a specimen and as a minor ore of lead.
Color
Yellow, greenish, sometimes colorless, grey, white brown and even reddish
Hardness
3.5-4
Specific gravity
7.1 Just pick up a mimetite and you will know that you have a heavy specimen in your hand.
Streak
White
Crystals
(Hexagonal) Prismatic, tabular, acicular and also surface growth.
Accompanied by:
Galena, cerussite, anglesite, pyromorphite, wulfenite and limonite
Similar to:
Pyromorphite, vanadinite, apatite, wulfenite and crocoite.
Mimetite is one of the lead minerals that makes interesting collectors items.
They are often found in association with other minerals that sets it of and shows up its color. The fracture is conchoidal to uneven. It has an adamantine lustre with a greasy feel. The crystals can be translucent to transparent.
We have dozens of Tsumeb mimetites that occured in the oxidation zones of the lead ore veins. It is one of my favourite collectors minerals.
Some decent mimetites have recently been mined in Thailand.
Mimetite at Tsumeb
The initial discoveries of mimetite during the twenties drew the attention of the collectore around the world to this mineral. Before that time the finest mimetite specimens were known from Johannheorgenstadt, Germany. This material was surpassed by the large, rich specimens of mimetite crystals of Tsumeb.
Prisms of yellow-green, 6 cm crystals form outstanding specimens. The finest crystals were found at a depth of 300 meters. At first they thought they had pyromorphite, the phosphate lead mineral. But all those labelled as such turned out to be mimetite. Other psuedomorphs were mimetite after bayldonite or duftite and arsetsumebite. It is estimeted that there must have been mimetite crystal up to 30 cm in length in Tsumeb.
In 1970 a pocket was hit which contained 30 crystals of exciting appearance. Crystals of 5-6 cm gemmy crystalson matrix. In addition to these outstanding mimetites, a large variety of shapes and colors have been found. During the last year of operation a large 12 cm crystal was taken out similar in appearance to a yellow ball point pen.
