This is a neat one of these – a bright metallic pyrite cube on matrix, with some complexity to it. At the top corner of the main crystal, you can see where a second small cube was beginning to grow, in virtually the same orientation as the large one but slightly offset. There are also a couple of subtle steps on the other faces. the crystal measures 2.9 cm across (2.0 cm on a longer edge). In excellent condition. Stands perfectly for display as photograhed.
About these Pyrite Crystals from Navajún, Spain
These are top quality specimens from the world's best locality for cubic crystals of pyrite. They are so perfect they do not look natural.
These pyrite crystals have an essentially uniform colour and a nearly uniform mirror-bright lustre from one crystal to the next, so if the colour or lustre on any two Navajún pyrite crystals on this site look drastically different from one another, it's the photography (the only way to photograph these is to set reflectors to catch each face, so the difference in appearance in photographs has to do with the reflectors, not the crystals themselves). These crystals are all a very pale silvery brassy metallic colour. They are all razor-sharp.
If you would like to see more about where they come from and how they look when they are still cubes in the rock in the mountainside, see The Incredible Pyrite of Navajún, Spain. In this post, you will see photographs of the crystals as they occur, and you can read my description of the extraction and preparatory work necessary to preserve these beautiful specimens. In particular, please note that the matrix is a soft, crumbly clay-like material and almost all of the pyrite crystals detach from it during extraction.
Virtually all matrix pyrite crystals from Navajún have been replaced back into the matrix in which they formed. The crystals and matrix are collected carefully, kept together, taken to the laboratory and re-assembled to repair them to the way they occured in the ground, before the collecting process disturbed them. Some of the intergrown crystals have been repaired and some have not. In general – closely intergrown ones have usually not required repair. Pyrite fractures and chips badly when damaged, so damaged crystals can rarely be repaired, but if intergrown crystals come apart leaving a very clean contact surface, repair is possible.
A few important notes about caring for these pyrite specimens: (1) Never clean them with water – the matrix will disintegrate and the crystals will fall out – dust them with a Q-tip or something similartly soft. (2) They are very brittle – if they fall over or are rested on a cube corner, they will chip. (3) It is best not to touch the crystals themselves with your fingers, or if you can't help yourself, wipe the fingerprint off right away – oils from human skin can permanently leave a mark and tarnish them over time.