PYROCHLORE
Specimen pyc-1

Dims: 0.8 x 0.5 x 0.5" (2.0 x 1.3 x 1.3 cm)

Wt: 8.5 g w/ base

Oka, Quebec, Canada

At least one complete Pyrochlore crystal rests in the complex host rock of this small thumbnail specimen. The crystal is quite small, not exceeding 0.3" (8 mm) along any axis, but has somewhat warped but good octahedral form- its edges are well-defined and its faces are clean, possessing a slightly dull, submetallic luster. Its color is brownish-black and it is completely opaque in halogen light. The host rock in which it is embedded appears to be made up of compact, granular quartz with random pseudohexagonal biotite "books" that are in surprisingly good condition. The piece is hot-glued onto an acrylic base.

Dims: 0.9 x 0.6 x 0.6" (2.3 x 1.5 x 1.5 cm)

Wt: 12.0 g w/ base

Oka, Quebec, Canada

This small thumbnail specimen consists of two visible and complete Pyrochlore crystals that are partly embedded in a black-and-white granular host rock. The crystals have dimensions of 2 x 2 x 2 mm and 0.3 x 0.2 x 0.2" (8 x 5 x 5 mm), and are in excellent condition, showing no visible damage. Their octahedral form is very good, as they have well-defined edges and clean faces. Their color is black, their luster is submetallic, and they are both completely opaque. The surrounding host rock seems to be made up of granular quartz and well-formed pseudohexagonal "books" of biotite that were compacted into a rock of sorts. The piece is attached to an acrylic base with hot glue.

Dims: 0.8 x 0.7 x 0.7" (2.0 x 1.9 x 1.8 cm)

Wt: 5 g

Minas Gerais, Brazil

This thumbnail specimen consists of a single Pyrochlore octahedron. The crystal is in good condition. showing light damage on a few of its corners, and has good octahedral form, though some of its edges and surfaces are not quite even. The crystal has a dark brown color and a dull, matte luster and is not attached to any base or host rock.

Dims: 1.3x0.6x0.6" (3.4x1.6x1.5cm)

Wt: 0.43 oz. (12.3g)

Veshnovorgorsk, Chelyabinsk Oblast, Russia

This thumbnail has one large, nearly complete octahedral crystal of pyrochlore, along with several visible fragments of additional octahedrons, on a host rock of calcite and biotite. This specimen is only slightly radioactive, barely above background levels. The brownish-orange crystals are translucent and have many internal fractures which reflect orange highlights when the light hits them. The luster is vitreous, although the crystal surface is rather uneven (looking a lot like the surface of mica crystals).

Dims: 1.3x0.9x0.9" (3.4x2.3x2.2cm)

Wt: 0.69 oz. (19.4g)

Vishnevogorsk, Ural, Russia

A single pyrochlore crystal rests in the white crystalline matrix of this specimen. The pyrochlore crystal is brown, somewhat distorted in shape (with two faces at 90 degrees), and has a wet vitreous luster. The crystal is dimply translucent, with a myriad of internal fractures. In direct sunlight, the fractures reflect yellow, orange, or even red highlights, depending upon their depth. There is also an abundance of black biotite crystals adding contrast to the host mineral.

Dims: 0.99x0.94x0.89" (2.50x2.38x2.27cm)

Wt: 0.57oz (16.3g)

Vishnevogorsk, Ural, Russia

Dozens of nice crystals of pyrochlore adorn all sides of this specimen. They look quite a bit like some garnets, with a bright luster, brown color, and orange highlights from internal reflections (revealing translucency). And while some of the crystals have a complex, garnet-like shape, others are clearly cubic or octahedral. Careful examination suggests that even the garnet-like chapes are really octahedrons with all corners flattened, resulting in a crystal with 14 sides. The off-white host rock looks like a white, translucent feldspar, judging by areas of cleavage.

Dims: 1.20x1.08x1.01" (3.05x2.75x2.57cm)

Wt: 0.93oz (26.5g)

Vishnevogorsk, Ural, Russia

Most of the pyrochlore crystals on this specimen are damaged, but that just reveals the color and transparency of the thinner sections. The pyrochlore is brown with orange highlights, and has a vitreous luster. The host rock appears to be composed of both calcite and a feldspar of some kind, with hundreds of tiny pyrochlore crystals included.