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Book X lapis sabinicus, lapis selentinus, lapis liparaeus and other mixtures of stone, metal and earth

Book X lapis sabinicus, lapis selentinus, lapis liparaeus and other mixtures of stone, metal and earth Page of 251 Book X lapis sabinicus, lapis selentinus, lapis liparaeus and other mixtures of stone, metal and earth Text size:minus plus Restore normal size   Mail page  Print this page
204
DE NATURA FOSSILIUM
fourth since minerals containing an earth and a metal are sometimes as hard as stone. As regards translucency, minerals of the second genus are not translucent since neither earth nor metal is transparent. Thus trans­parent minerals must belong to the other three genera. The proper one is determined by smelting. Minerals of gold, copper and other metals are classified in the same manner.
Species of these genera are usually classified by color. One genus em­braces many species, another few, as I shall explain presently. Since the species of the silver minerals are better known to our miners than those of the other metals I shall consider them first. There are lead-colored, gray, black, white, red, purple, liver-colored, and yellow silver minerals. The lead-colored mineral whose name we derive from plumbum, is known to the German miner by a name derived from glass.2 Actually it lacks the true color of galena and is not transparent as is glass from which the name is seen to have been derived. Sometimes it is the color of galena although darker. The two are similar but anyone acquainted with mineral substances can distinguish one from the other by eye. Nature has pro­duced this mineral from a large amount of silver and a small amount of earth. Galena, composed of lead and stone, sometimes contains silver. The two have distinctive features. Galena can be pulverized with a pestle in a mortar while argentite flattens out. When galena is struck with a hammer or knife or compressed between the teeth it flies apart while argentite spreads under the flow of the hammer, can be cut with a knife and is compressed between the teeth. There is a hard silver mineral be­longing to this same species that cannot be distinguished from galena by eye but only by smelting. However, it is readily recognized by experts. Whether a mineral contains a metal and stone, or earth is determined by smelting, as I have said. If it contains stone it is usually a lighter color. Both the hard and soft silver minerals have their characteristic true color inside while on the outside they may be black, yellow, or some alien color. Hammering immediately brings out the true color.
Native silver takes first place, argentite second. Ninety pounds of silver is obtained from one hundred pounds of the purest mineral.3 From this we know that the pure mineral contains less than a tenth part of earth since some of the silver is burned away and some goes into the slag. This mineral is uncommon at Rhetia, Noricum, and Dacia, and common in Germany although it is not found in all the silver mines. It is most abundant in Misena at Schneeberg, Scheibenberg, Garium, Marienberg, Annaberg; in Bohemia at Abertham in the Joachimstal valley and in nearby mines. Sometimes a portion of a vein is twenty-four to thirty or
2 Latin, argentum rude plumbei coloris; German, glaserze; English, argentite, silver sulphide.
3 Pure argentite contains 87.1% silver and is often more or less intimately associ­ated with native silver.
Book X lapis sabinicus, lapis selentinus, lapis liparaeus and other mixtures of stone, metal and earth Page of 251 Book X lapis sabinicus, lapis selentinus, lapis liparaeus and other mixtures of stone, metal and earth
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