Bornite Bornite has a brown to copper-red color on fresh surfaces that tarnishes to various iridescent shades of blue to purple in places. Its striking iridescence gives it the nickname peacock copper or peacock ore.
Chalcopyrite has a golden yellow color, which often resembles Gold. However, its physical properties such as streak and tenacity are very different from Gold and can easily distinguish it. Chalcopyrite is a beautiful mineral and good crystals and specimens are fairly common, leading it to be a very popular mineral. "Peacock Ore" which is sold to many amateur mineral collectors often as a variety of Bornite, is in fact almost always Chalcopyrite that is treated with acid to produce an iridescenttarnish.
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 aresecondary 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 exhibitoctahedral 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 cleavedspecimens 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.
Pyrite is commonly called Fools Gold because of its similarity in color, shape, and habit to Gold. In the old mining days, Pyrite was often confused with Gold as they occur together, although Gold and Pyrite can very easily be distinguished by simple observation and testing of characteristics.
Pyrite occurs in all different shapes and forms. The smaller crystal aggregates may give off a beautiful glistening effect in light, and the larger crystals may be perfectly formed, including fascinating perfect cube and penetration twins and other bizarre crystal forms. The perfect cubes of Pyrite embedded in a matrix from the famous Spanish mines are especially treasured among collectors. Many of these specimens have fallen out of the matrix and have been repaired by having them glued back into the matrix.
Pyrite has the same chemical formula as the rarer mineral Marcasite, but it crystallizes in a different crystal system, thereby scientifically classifying it as a separate mineral species. Aggregates of iron sulfide (FeS2) where the crystal structure cannot be determined without complex analyzing material may be wrongly labeled by dealers. Some Pyrite specimens are labeled as Marcasite, and some Marcasite specimens as Pyrite.
Sphalerite is a common mineral, and occurs in many distinct colors and forms. Iron impuritiesare often present in this mineral, and for this reason it is not commonly transparent. If Sphalerite contains a large amount of iron impurities, it will have a metallic dark gray or black color, which is typical of most sulfide minerals. Sphalerite is one of the few minerals that can range from gemmytransparent crystals to dark, metallic-black crystals.
An interesting variety of Sphalerite is known as Schalenblende. Schalenblende is banded variety associated with Wurtzite and often also Pyrite and Galena that forms strange concentricshapes. It is often polished into slabs or cross-sections which are very popular with collectors. Schalenblende is known from a select few mineral in Europe, most notable is the Segen Gottes Mine, Wiesloch, Baden-Württemberg, Germany.