SILVER
This piece of silver ore is from a silver vein 5,400 feet under ground in the Sunshine Mine, a famous north Idaho silver mine in Silver Valley. (I read somewhere, if this is the same one - (Kellog?) that there was a disaster there in 1972; the worst in the state's history - will try to check it out). This ore is very heavy for its size; there is silver, gold, lead, copper and zinc in it - as well as white quartz.
Silver usually occurs in massive form as nuggets or grains, although it may also be found in wiry, dendritic (tree-like) aggregates. When newly mined or recently polished, it has a characteristic bright, silver-white colour and metallic lustre. However, on exposure to oxygen in the air a black layer of silver oxide readily forms, tarnishing the surface. Because of this, and the fact that it is too soft to be used in most jewellery in its pure form, silver is often alloyed with other metals, or given a covering layer of gold. Electrum, an alloy of gold and silver in use since the time of the Ancient Greeks, contains 20-25 per cent silver. Sterling silver contains 92 1/2 per cent or more pure silver (and usually some copper), and Britannia silver has a silver content of 95v per cent or more. Both alloys are used as standards to define silver content.
Most silver is a by-product of lead mining, and is often associated with copper. The main silver mining areas of the world are South America, the USA, Australia, and the former USSR. The greatest single producer of silver is probably Mexico, where silver has been mined from about AD1500 to the present day. The finest native silver, which occurs naturally in the shape of twisted wire, is from Kongsberg, Norway.
Hardness: 2 1/2