BOULANGERITE
Specimen bul-3
$ 130.00Dims: 3.3" x 3.0" x 1.2" (8.4 x 7.6 x 3.0 cm)
Wt: 7.25 oz. (205.7 g)
Hulcani Mine, Ancash, Peru
This hand specimen consists of scores of gray metallic Boulangerite needles resting among two other minerals on a gray quartzite slab. The Boulangerites achieve lengths of over 0.5" (1.3 cm), but are all at least as thin as human hair. Though a few of them are gathered in radiating sprays, most seem to be randomly arranged. They grow among scores of large, blocky siderite crystals that have a pale brown coloration and a pearly luster. These crystals range in size from a few millimeters to over 0.5" (1.3 cm) in each dimension and show excellent trigonal prismatic form that appears almost pseudo-octahedral in the largest crystals. They all are most definitely opaque. Also accompanying the Boulangerites are several pyrites or chalcopyrites, most of which seem to be either twinned or heavily intergrown. Their form appears to be either cubo-octahedral or a variation of the disphenoid, but it is very difficult to tell. There are several more of these pyrites on the other side of the quartzite host rock, along with a few more Boulangerite needles and what appear to be some tiny tennantites or tetrahedrites. Although this specimen's documentation says that the golden crystals are pyrites, their form and depth of color have more or less convinced me that they are chalcopyrites.