The main ore types mined at Rosh Pinah are carbonate ore, microquartzite ore, and arkose ore containing mainly the sulphide ore minerals sphalerite (ZnS), galena (PbS), chalcopyrite (CuFeS2) and Pyrite (FeS). Specimen grade sphalerite crystals are occasionally found as attractive dark brown metallic euhedral cubes in vugs and quartz veins in this mine.

Photo. G Hinder

They can also occur as an adamantine lustre of golden brown and even yellow green colour, but not at Rosh Pinah. These crystals can be facetted, but at a hardness of 3 to 4 their primary use would be as a collector’s stone. They can be very beautiful when cut, and have a dispersion three times as high as that of diamond.

Zinc is a very useful metal with about 50% of the world's production being heated in tanks to melting point and having steel dipped into the tank and thus coated with a layer of this molten soup to prevent the steel from rusting on exposure to the elements. In Paris in 1860 it was made mandatory to use galvanized rolled sheets and the whole city underwent a transformation creating the attractive roof scape that became famous and inspired many painters. Even further back in time, during the excavation of Pompeii which was destroyed by Vesuvius in AD79 a zinc capped fountain was discovered showing that zinc is a material of long standing.

The campfires of our forefathers probably led to the discovery of a few metals. When metal oxides are heated, the carbon combines with the oxygen leaving a more or less pure metal behind. This would not have been true for zinc as when it is heated to red heat the metal boils and goes up in smoke. The ancients used to use a solution of hemimorphite (calamine or zinc silicate) to add to copper to make brass.

The first batteries that were made utilized zinc as an anode and carbon as a cathode. So, when you next look at your gleaming sphalerite specimen think of what a useful metal it represents to humankind.   CS