David K. Joyce

Downs Collection, Arizona Minerals

I am pleased to offer the mineral collection of Dr. Robert T. Downs for sale, here on the website. Dr. Downs was born and raised in Canada and lived in many places across the country. Since a boy he was interested in minerals and mineralogy and has had several mineral collections over the years. Bob was a “late starter” and, after many years working on major construction projects as a supervisor and surveyor In British Columbia and the Yukon, he finally completed a degree in mathematics at the University of British Columbia, at the age of 30. Subsequently, he completed a masters degree and then a PhD in Mineralogy and Mathematics at Virginia Polytechnic. All through his life, he collected and studied minerals and was especially good at field collecting fine and interesting mineral crystal specimens. After post-doctoral studies at the Geophysical Lab in Washington, DC, he accepted a professorship at the University of Arizona, in Tucson. He has contributed much to the world of crystallography and mineralogy over the years, in the field of crystal structures, the RRUF project, supervision of dozens of masters and PhD students, as founding curator of the New Alfie Norville Gem and Mineral Museum in Tucson and in remote sensing and mineralogical analysis for extra terrestrial missions.
The Downs collection reflects his interests over the years, particularly with the Apatite Group of minerals, fluorapatite, vanadinite, mimetite, pyromorphite, etc. As well , other specimens are some very good personally collected specimens from Southern Arizona. There are a number of other pieces that just intrigued Bob for various reasons. Here are some of his mineral specimens.

In this page, you will find specimens that Dr. Downs collected in Arizona at various times, over the years.

All prices in Canadian dollars. For payment in US$, deduct 18% or multiply by 0.82.

Click on any of the following thumbnails to view a larger image of the specimen.

Item #27845 Quartz, var. Chalcedony, opal 6.2x3.1x3.9 cm Largest Crystal Size: n/a $65.00 Deer Creek Willcox Arizona, USA RTD There is an area north of Willcox, called Deer Creek where an unusual type of silica forms. In fractures between basalt fragments, silica in the form of white chalcedony, brownish chalcedony , white opal and quartz crystals form. The brownish chalcedony can have an odd iridescence, when ground and polished the right way. Then is it referred to as "Fire Agate". This piece may have this play of light. The white opal fluoresces a bright green. The back of the specimen is a sort of geode lined with drusy quartz crystals. Very nice example collected by Dr. Downs in 2009.	Item #27867 Wulfenite 9.0x7.2x4.0 cm Largest Crystal Size: 9mm $95.00 Red Cloud Mine La Paz County Arizona, USA RTD Two, beautiful, orange-red wulfenite crystals are nicely exposed on this piece. The matrix is composed of willemite (fluorescent greenish) plus other vein minerals. Lots of black coated willemite crystals around the wulfenite. The wulfenite crystals are thick-tabular with truncated edges and small corner faces. Shows well. Collected in 1997.	Item #27868 Vanadinite, Calcite 5.2x4.2x1.0 cm Largest Crystal Size: 4.5mm $65.00 Hamburg Mine La Paz County Arizona, USA RTD The Hamburg Mine is renowned for its gemmy, ruby-red vanadinite crystals here is a good example. The crystals re sharp hexagonal prisms with wonderful complex terminations. The crystals grew in a tight crack so the larges ones have the imprints of calcite crystals on their sides from the crystals on the other side of the crack. Nice!	Item #27869 Vanadinite, Calcite 6.7x4.7x3.7 cm Largest Crystal Size: 3mm $45.00 Hamburg Mine La Paz County Arizona, USA RTD Several, sharp, deep red, gemmy vanadinite crystals are scattered around the center of this calcite crystal coated matrix. The vanadinite crystals, although small, are beautiful, hexagonal prisms with very sharp terminal caces composed of pinacoid and pyramids.
Item #27870 Vanadinite 2.8x1.7x1.4 cm Largest Crystal Size: 3mm $35.00 Old Yuma Mine Pima County Arizona, USA RTD This small matrix is largely covered by bright, hexagonal prisms up to 3mm in length. Old AZ classic!	Item #27873 Vanadinite, petrified wood 2.7x1.7x2.7 cm Largest Crystal Size: 4mm $65.00 Empire Ranch Pima County Arizona, USA RTD These specimens are a bit peculiar. Bob was exploring the back country, on the Empire Ranch and came across a petrified log that had open spaces in it, lined with well formed vanadinite crystals. This is a good example showing brown vanadinite crystals on fine grained fossilized wood.	Item #27877 Wulfenite 3.2x1.9x1.8 cm Largest Crystal Size: 6mm $45.00 Pure Potential Mine La Paz County Arizona, USA RTD Just a little guy, but nice crystals from an unusual wulfenite locality. Bob collected these specimens with George Godas in 1997.	Item #27878 Wulfenite. Quartz 7.1x4.1x3.0 cm Largest Crystal Size: 12mm $170.00 Pure Potential Mine La Paz County Arizona, USA RTD The red-orange crystal on the right practically glows. This very nice crystal is one of two in a quartz lined vug that fills the front of this specimen. A few willemite crystals here and there. Collected with George Godas in 1997. Displays very well.
Item #27882 Vanadinite, Calcite 7.5x4.7x2.9 cm Largest Crystal Size: 3mm $65.00 Pure Potential Mine La Paz County Arizona, USA RTD Lighter coloured, bright, vanadinite crystals from the Pure Potential mine. Gemmy crystals associated with white-colourless calcite crystals. Collected with George Godas in 1997.	Item #27982 Wulfenite, Willemite 9.3x6.4x5.2 cm Largest Crystal Size: 7.5mm $75.00 Red Cloud Mine La Paz County Arizona, USA RTD Some very nice, well formed orangey wulfenite crystals on tis specimen, along with small elongated crystal bundles of willemite, that fluoresces green. Classic AZ!	Item #27985 Vanadinite 2.2x2.1x0.8 cm Largest Crystal Size: 4.5mm $35.00 Pure Potential Mine La Paz County Arizona, Canada RTD A nice little specimen, representative of the very red-orange vanadinite from the Pure Potential Mine. Simple hexagonal prisms with pinacoid termination and slight beveling pyramid faces.	Item #27987 Vanadinite 2.6x2.1x1.3 cm Largest Crystal Size: 4.5mm $40.00 Old Yuma Mine Tucson Arizona, USA RTD A nice little specimen showing perfect, orange-red, hexagonal prisms of lustrous vanadinite.
Item #27989 Wulfenite, Mimetite 5.4x3.7x2.5 cm Largest Crystal Size: 5mm $45.00 Red Cloud Mine La Paz County Arizona, USA RTD The cavity on the top of this specimen has a number of sharp, tabular, orange-red wulfenite crystals in it. Of particular interest is the elongated habit of some of the crystals. As well, the cavity is largely lined with red, prisms of mimetite. Nice!	Item #27990 Wulfenite, Willemite 7.8x5.3x3.5 cm Largest Crystal Size: 7.5mm $45.00 Red Cloud Mine La Paz County Arizona, USA RTD The top of this specimen has a couple of well formed, tabular, orange wulfenite crystals, associated with ting, prismatic crystals of willemite. Such great crystals of wulfenite from this famous mine!	Item #27993 Azurite, Malachite 5.5x4.0x3.2 cm Largest Crystal Size: 5mm $195.00 Copper Queen Mine Bisbee, Cochise Co. Arizona, USA RTD This mound of gossanous matrix is covered with a black compound, perhaps a manganese oxide. This in turn is heavily speckled with small 1mm tufts of green, acicular malachite crystals. Concentrated, in a number of spots are deep blue, bladed, gorgeous azurite crystals. Nice piece from one of the greatest mineral localities of all time!