Chalcopyrite & Tetrahedrite

Description

Both Chalcopyrite and Tetrahedrite have a hardness of 3½ – 4, and while Chalcopyrite is a little less dense with a specific gravity of 4.1 – 4.3, Tetrahedrite isn’t very much more dense with a specific gravity of 4.97.

Chalcopyrite was named in 1725 by Johann Friedrich Henckel, and gets its name from the Greek words “chalkos”, for copper, and “pyrites”, for strike fire. There’s quite the group of minerals when it comes to pyrites, but this is definitely one of the most common, for sure, with more than 31,884 recorded localities on Mindat! It’s usually found “in hydrothermal veins, disseminations, and massive replacements; the principal copper mineral of porphyry copper deposits” according to Mindat. Also stated on that page is that Chalcopyrite is the “most abundant copper-bearing mineral and is widespread.” WebMineral shows a sample they analyzed at nearly a 33% split between Iron, Sulfur and Copper.

According to Wikipedia, “Tetrahedrite gets its name from the distinctive tetrahedron shaped cubic crystals… it is a steel gray to black metallic mineral which occurs in low to moderate temperature hydrothermal veins and in some contact metamorph deposits. It is a minor ore of copper and associated metals. It was first described in 1845 for occurrences in Saxony, Germany.” According to Mindat, tetrahedrite was “originally called ‘Argentum’ by Georgius Agricola (Georg Bauer) in 1546 because it contained silver, although it may not have necessarily been silver-dominant like the related mineral, freibergite, is”.

As antimony isn’t an element you should bring home in abundance, consider skipping on bringing this home – unless you need a sample of the element. However, the copper in this rock makes this one valuable rock to find on your next hike, so keep your eyes out for Tetrahedrite and Chalcopyrite!