Galena minerals are a type of mineral whose main ingredient is sulfide and mainly made up of lead sulfide. This belongs to the class of the sphalerite group of minerals and is usually associated with hydrothermal veins and is a typical secondary ore of lead. Galena has been mined for over thousands of years for its lead content and also remains fresh and relevant for its industrial applicability even today.
The minerals related to Galena are such that they exhibit a metallic kind of shine when seen in the twinkling of an eye, and their basic color is that of grey. It has been so densely packed it is fairly heavy, and it is rather easy to separate from other minerals. Some of the other impurities that are found in the mineral include Argentiferous, cupreous, zinciferous and other associated metals.
Galena is easily identifiable. Newly cracked parts are perpendicular accurate cross-sections located at 90 degrees with each other. The cilia are of silver colour and they give a brilliant metallic look. The once shining Galena turns into a washed out grey tone. Since lead is one of the major constituents of galena the mineral is characterized by a very high specific gravity which is apparent even when the mineral is in small grains or lumps. Galena is a soft mineral with Mohs hardness of about 2 and can be easily shaped. 5+ and a stain colouring that goes from grey to black. The shapes of crystals are often cubic, octahedral, or something halfway between the two (mixed).
Physical Properties of Galena in table form
Here are the key physical properties of the mineral galena presented in a table:
Property Description
Chemical formula PbS
Color Lead gray to silvery metallic
Streak Gray to black
Luster Metallic
Crystal system Cubic
Hardness 2.5 – 3 on Mohs scale
Specific gravity 7.4 – 7.6
Cleavage Perfect cubic
Fracture Subconchoidal to uneven
Solubility Insoluble in water, soluble in hot concentrated nitric aci
Silver-Bearing Galena – The Silver Ore
Historically it was also noted that the average galena sample has an average composition of roughly 86. 6% lead and 13. 4% sulphur by weight. However, there are well-crystallized specimens of galena that could contain a few percent by weight of silver. They are called argentiferous galena due to their silver composition. In these specimens, instead of replaced lead in the atomic structure of the galena, silver may co-exist as small granules of the silver minerals in the galena.
Silver dissolved on the galena breaks the crystal lattice; majority of the galena has curved cleavage parts. What little is known about this creature can be effectively used in such a capacity as a prospecting tool. The following impurities may also be present in Galena basically in very small proportions; antimony, arsenic, bismuth, cadmium, copper, zinc and also silver. In addition, the impurities consist of less frequently selenium substitutes sulphur in galena.
Galena Value
In some cases, some mines experience earning more from the value of galena in terms of silver more than that of lead. Suppose that a mine has an average of mostly argentiferous galena having the composition of 86% lead, 13% sulphur and 1% silver only as shown in the diagram below.
In that case meaning that the price of troy ounce of silver is $25 while that of avoirdupois pound of lead is $1, the value of lead in one tonne of ore is $1720 while the value of silver will be $7292 as can be seen in the diagram on this right.
The small amount of the silver has the large impact on the overall revenues due to the fact that based on the assumed prices the silver is 364 time more valuable than the lead of the same weight . Thus, it becomes rather easy to understand why mining firms and corporations are so keen on putting their money where argentiferous galena is! Now a days these mines may be described as “silver mines “although galena is the extracted substance and lead is the main product.
Refining Galena
Believe me, it is very easy to dissolve galena in water or any liquid like those mentioned above at very high temperature. Wherever there are galena-containing rocks, such as galena-iron pyrites ore, lead may be collected from under ashes after the fire has been extinguished. Copper’s smelting has been done by people for many centuries using this relatively simple method. Lead glittering and statues belonging to as early as 6,500 B. C. E. has been found in Turkey, and yet most historians agree that lead is probably the first metal to be sought from its ore. Romans used lead conduit for house plumbing. The word ‘plumbing’ and chemical symbol ‘Pb’ for lead are derived from the Latin word ‘plumbum’, words that originated from the Romans.
It was in the eigteenth century that engineers and miners became capable of using natural methods of separating silver from lead. Genuine Roman lead examples signed ‘Ex Arg’or ‘Ex Argent’ in Latin meant that the silver had been taken out. The Greeks were able to desilver lead to 0 down to the point that the problem of deflation started to emerge. 02 percent, while the Romans were able to desilver lead down to 0. 01 percent. I stand in amaze considering that they were able to deduce that the lead had silver and that the process that they employed was so efficient!
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