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What's New and Cool at the Denver Gem and Mineral Show
Much To-Do Over Manganese Carbonate

Well, the bad news is that I unpacked my video camera after returning to Tucson to proceed with frame grabbing more content for this show report, and either something's gone south with the tape head alignment or transport drive, causing nasty white streaks in the video when it's played back, or else it just needs cleaning... :(
I'll be acquiring a new cleaning cartridge asap and hopefully that's the fix.

The good news is that when I initially visited The Collector's Edge's room at the Merchandise Mart, the powers that be would not allow me to use my video camera to do report acquisition in their room (it's some kind of Collector's Edge policy thing). So I returned the next day with my trusty Nikon and shot some stills, which I'm able to scan and present without needing my ailing video camera.

The Collector's Edge operates Colorado's Sweet Home Mine, which was rather unsuccessful as a silver mine, but now a legendary locality for it's aesthetic rhodochrosites. Rhodochrosite is manganese carbonate, mined as an ore of manganese where found in large masses. It is a common, semi-hard mineral in the hexagonal crystal system which occurs in granular, concretionary or stalactic masses, and more rarely as rhombohedral or scaleonhedral crystals. Rhodochrosite forms in hydrothermal veins associated with other manganese minerals and copper, silver, and lead sulfides, as well as a sedimentary mineral in the oxidation zone of sulfide deposits.

The display cases at the Collector's Edge were loaded with Sweet Home rhodos and were undoubtedly among the most heavily trafficked and viewed cases at the Denver Show. Interest in their offerings is always high and was further fueled at Denver this year by a recently published special issue Mineralogical Record on the history and story of the Sweet Home Mine and its minerals.

One of The Collector's Edge cases is shown at left, from a vantage point behind it. Many of the viewing collectors and browsers seemed as awestruck by the truly astronomical prices the finest Sweet Home rhodos were commanding as they were by the remarkably beautiful rhombs themselves.

The origin of the name rhodochrosite comes Greek, for rose and color. While the ancient rockhounds never knew rhodo specimens as fine as these, the reference is certainly appropriate. If you want to score some major points with a rockhound honey, lose the flora Bub, and give her a Sweet Home rhomb!

The specimen shown above left is from the Sweet Home's Clay Pocket and features 3 large crystals on matrix. Each rhomb looked to measure a little better than an inch on edge. This specimen wanted $12,000 in spite of being repaired. Rhodochrosite crystals exhibit perfect rhombohedral cleavage and are rather fragile.

The specimen shown above right is from the Strawberry Pocket and was about six inches across. In addition to the big rhodo rhombs it was sprinkled with a baker's dozen fluorite crystals, the largest of which was a dodecahedron about the size of an English walnut! These associated fluorites are highly prized by collectors and really add a lot of zing to the specimens they occur on. Of course, they really add a lot of zing to the price too. This one was offered at $40,000.

I'm not positive they were referring to this particular specimen, but while I was taking this piece in, I overheard a conversation between two dealers who were standing close behind me. They were remarking how they were surprised some particular party had passed on the $40,000 specimen, as they considered it cheap at the price. Now really, there's an oxymoron for you - a 'cheap' $40,000 rock! I know Einstein theorized all things are relative, but I'm afraid this old rockhound is still operating with a somewhat Newtonian mindset...

Of course The Collector's Edge offered rhodos for indigent rockhounds too. There were about 20 flats of less expensive material about the room, starting at $10 or so and running on up into the hundreds of dollars. Needless to say, $10 doesn't go too far in the Sweet Home rhodo department.

The Collector's Edge offered mostly upscale specimens of many other species from various world-wide localities as well. Among them were a number of Colorado amazonites, with and without associated smoky quartz. The specimen shown above right was one of the more aesthetic to my eye. This specimen is from the Tree Root Pocket of the Two Point Mine, Teller County, Colorado. It was repaired, which is not uncommon for these larger amazonites, and was offered at $2000.

Here's a couple more Sweet Home Mine rocks which were displayed by The Collector's Edge in a case in the main arena of the gem and mineral show. The chunky rhomb on quartz shown at left was mined in September 1992 from the Good Luck Pocket, Main Stope. I estimated this crystal to measure a little shy of 2 inches on an edge.

The faceted rhodo on the right wore a fancy cushion type cut well, and it easily exceeded an inch across, weighing in at 92.3 carats. Rhodochrosite must be a rather challenging material to facet. It is brittle and fragile with a hardness of 3.5 - 4.0 and has perfect rhombohedral cleavage (three directions). Rhodochrosite exhibits very strong birefringence (that is, it is multiply refractive with RIs at 1.60 and 1.82) and weak dispersion. Orientation of the stone in the rough would need to take into account both the optics and cleavage planes, in addition to inevitable flaws in rough larger than a few carats.

Just about everyone who passed by this faceted rhodo was oohing and ahhing over it. The color was pretty and unusual, and of course the size was striking, making this a unique and special gem. However, due to its high birefringence and low dispersion, it had a rather fuzzy and dull appearance to this cutter's eye. The mediocre optical properties of rhodochrosite combined with its difficult physical properties and the undoubtedly extravagant cost of facet grade crystal leads me to conclude that for general purpose recreational rock murdering, rhodochrosite rhombs are best cast off as leaverites for mineral collectors. ;)

Shown by The Collector's Edge, PO Box 1169, Golden, Colorado 80402 - By Appointment Only, Phone: 303-278-9724

Another related exhibit in the gem and mineral show main arena that I thought top notch was this Denver Museum of Natural History reproduction of a Sweet Home Mine crystal pocket, constructed by Jack D. Thompson with a grant from the Colorado Springs Mineralogical Society. There were a lot of nose marks on the glass covering this one, so I wiped it down before taking the close shot above right. Pretty nice display, don't you agree?

Okay, you Sweet Home rose rock freaks, ready for this one?

This humongous plate of rhodochrosite crystals on quartz & sulfides is from the Corner Pocket/Watercourse Raise of the Sweet Home Mine. It's overall dimensions are 24" wide x 12.75" high x 10" deep. It was shown by The Sunnywood Collection, and is depicted here as featured on a post card they created just for this specimen. Bill and Elsie Stone are renowned for the custom specimen stands and displays which grace their fine specimens. They showed many other spectacular and fine Sweet Home rhodos among the other specimens in their room at the Holiday Inn, but this one has a awesome presence that simply commands your attention.

The MR I referred to has a picture of this specimen in the mine before it was liberated from the surrounding matrix. If you have to ask, you can't afford this one. Okay, okay, alright already! - it's a virtual steal of a deal at only $100,000 and yes, that includes the stand.

The specimen shown at right was one of the other Sweet Home rhodos shown by the Sunnywood Collection. This one featured a large rhomb lording over several others as well as numerous fluorites on quartz and tetrahedrite.

This aesthetic piece was from the Butterfly Pocket, and it's attractively protected and well displayed by the rotating hardwood base and acrylic cover. This one was offered at $16,000.

Shown by Bill and Elsie Stone of The Sunnywood Collection

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