A superb example of pyrite, with crystals to 2.5 cm in a remarkably aesthetic tower of naturally connected crystals. Pyrite from this remote location , a short drive from the ancient Aragon capital in Zaragoza, sets a world standard for its sharp and precise crystal geometries. Pyrite is simply iron sulfide, two elements, bound together in a simple cubic matrix that produces, therefore, a cubic crystal. What you are seeing is billions upon billions of pyrite molecules stacked upon each other like Legos, that somehow formed in an unusually perfect and harmonious environment deep within the earth and gave us a perfect rendition of nature's geometry. Such sharp, perfect crystals are a rarity in any species, especially metallics. This location has been known since Roman times as ancient workings for iron, of which pyrite is the ore. The mine started production as a specimen mine only later under the previous owner's family (Pedro Ansorena). His father staked it after WWII as a lead mine, and later developed it as a specimen mine instead, choosing to work slowly and with care to save these amazing specimens from destruction simply to supply furnaces with ore. This location, for the quality it produces, is legendary among mineral collectors. A few pieces among every thousand are considered "top tier" compared to the rest, based on perfection and aesthetics overall. The so-called "castles" like this are among the most desirable, particularly when perched on natrual host rock matrix. Like all of them, it is stablilized; and has a few clean repairs, which is acceptable in and typical of this material. Today, they still produce pyrite specimens at this working mine, under new ownership; although the top quality remains as rare now as ever. The cluster is dramatic, 3-dimensional, and complete all around. For such a tower of crystals, they might find only one such specimen per several thousand crystals each mining season. Supported on a custom molded lucite display base.
6⅛ x 4½ x 3⅛ in. (15.6 x 11.5 x 8.0 cm.)

ex Pedro Ansorena collection

Mineral Explorers, 1 Oct 2016, PBS television: https://www.youtube.com/watch?v=sgjlUX2rnC4