The galena
Author:Network sources Source:Network sources Date:2013-04-22

Galena is the most common mineral containing lead, and has been well-known throughout the centuries. It is often well crystallized and forms in many interesting and distinct crystal shapes. Some cubic crystals have their edges cut by the partial octahedral growth, some octahedral crystals have their points flattened by cubic growth, and many crystals are found somewhat in-between cubic and octahedral. Dodecahedral growths may partially be found in octahedral or cubic-octahedral crystals, resulting in bizarre and interesting shapes.

Galena is a primary mineral. Most of the lead minerals, such as Cerussite and Anglesite are secondary minerals formed from Galena. Impurities in the structure of Galena, such as silver and bismuth, may change Galena's cleavage properties. Galena containing bismuth may exhibit octahedral cleavage, and silver in Galena may cause a specimen to exhibit flaky, slightly bent cleavage fragments.

Galena specimens may tarnish when exposed to air, becoming dull in luster. Freshly cleaved specimens exhibit a strong metallic luster, but over time the luster turns more dull, although still metallic. The tarnish can be removed by scrubbing the specimen with water and mild soap.

Galena specimens must be taken care of more so then other minerals. They are easily damaged, and well formed crystals may shatter into small crystal fragments if put under slight pressure or dropped, so care should be taken when handling and transporting Galena specimens.

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