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This is a riveting crystal of TOP QUALITY, with the best color, exceptional gem-grade gemminess to the top 1/3, and association with calcite to make it a nifty "matrixy" specimen instead of just another loose single as we so often see. The crystal has intense color, diminished slightly by the stunning clarity in the top portions but still very , very impressive, such that for combination of qualities I rate this very highly. The crystal is SHARPly hexagonal with exquisite form, complete all around save for one teeny ding on a back edge of the termination. As an estimate, there should be at least 20% recoverable facet rough of high quality in the top portion above the calcite attachments, so figure 8 carats. Even with loss to cutting, you can probably get a CLEAN 3-4 carat stone out of this, I would think (at $1500-2500 per carat fair value). However, I don't wish to take the cutting risk and its a tragedy to do that to a good thumbnail gem crystal! So, here is a piece whos eintrinsic value probably is MORE THAN its specimen price here, for those reasons.
Though Calcite is the most abundant carbonate in the earth's crust, and is known to every collector in a variety of colors and forms, it is not a very common gem because the material has perfect cleavage plane running in 3 directions, so only very skilled faceters can create well cut gems. This particular stone is a nice light yellow color, very slightly included gem with an Emerald cut. Due to the birefringence of Calcite, the pictures make the stone look a bit fuzzy, but it looks better in person.
ex. Richard Heck
This specimen features unusually flattened, lustrous and translucent calcites perched on colorless quartz crystals, to 1 cm in length. Associated with the quartz are splendent, brassy yellow crystals of chalcopyrite, to 1 cm across. The disk shaped crystals of lustrous and translucent, white calcite crystals, to 3.25 cm across, are then perched on both the quartz and chalcopyrite. Neat combo specimen!
ex. Richard Heck
Flowerlike, calenohedral, lustrous and translucent white calcite crystals to 2 cm in length are perched on top of a knob of brilliant and classic galena crystals for this locality. The contrast of color and texture is superb. Pristine!
ex. Richard Heck
Classic old material, the Santa Eulalia pyrrhotites are seldom seen on the market today in any quality. Superb, columnar, doubly terminated, pyrrhotite crystals, to 4 cm in length with good luster and a tan color , are partially covered by a druse of calcite. There are even a few lustrous and translucent, colorless fluorite crystals, to 5 mm across, attached to the pyrrhotite - I had not personally seen this association before out of thousands of Naica pieces I have seen since the 1980s. The crust of calcite fluoresces a dark reddish brown when lit in UV. The piece displays well horizontal or vertical
ex. Richard Heck
This combo specimen has a style and 3-dimensionality that make it unique! A druse of brassy yellow pyrite highlights splendent, black sphalerite crystals, to 1.5 cm across and superb rhombohedrons of frosted, lustrous and translucent, ivory colored calcite to 3.5 cm across. The way the calcites climb this specimen and surmount it is aesthetic and exceptional. Interestingly, the pyrites are , on close inspection, pseudomorphs after pyrrhotite and retain the bladed habit of the previous species. The calcite fluoresces a rich reddish-orange color due to manganese content, as a bonus. A wonderful example of sufides and carbonates!
ex. Richard Heck
A dramatic and sculptural specimen ! Here, a second generation druse of sparkling, snow white, calcite has grown on a cast of what was once robust calcite rhombohedrons (now hollowed out and cast over by 2 generations of later calcite. The calcite rhombs reached 7.5 cm in length. The calcite fluoresces an intense, deep orangey red color (due to manganese). This is a really dramatic piece, for form and stark simplicity of color/form
ex. Richard Heck
Complex once you look closely...A rhombohedral, lustrous, white, calcite crystal of 4.5 cm across is emplaced on a sulfide matrix along with a few crystals of lustrous and translucent, colorless fluorite crystals to 1 cm across. Most of the calcite rhomb has then been enveloped by a doubly terminated, large, second-generation calcite crystal that mesaures 8 cm across, exhibiting numerous dog tooth terminations. This crystals is lustrous and translucent, ivory colored; and as a bonus it fluoresces a superb, deep, reddish- orange color. Oddly, the original rhomb has a surface fluorescence of light purple. This is an interesting and aesthetic specimen
ex. Richard Heck
A core of intergrown, glassy and gemmy, nearly colorless fluorite crystals (with a faint straw color), to 1.6 cm across is almost covered on both sides by rosettes of lustrous, light-brown calcite crystals, to 2 cm in length. Unusual in its aspect, and complete all around
ex. Richard Heck
Like a flower perched aesthetically on a matrix of drusy, splendent, galena, is a cluster of lustrous and translucent, milky white calcite. The cluster measures 4.5 cm across. The calcite fluoresces a spectacular, bright orange color (due to minor manganese). Neat association specimen with great aesthetics!
ex. Richard Heck
Perched aesthetically, high on a matrix of drusy calcite, are several glassy and gemmy, colorless, calcite crystals to 2.6 cm in length. The longest crystal is also doubly terminated (though with very slight edge wear on one tip, which can be removed with acid if desired). The calcite crystals are absolutely limpid and the form is highly unusual
ex. Richard Heck
A glassy and gemmy, pink danburite crystal, measuring 4.8 cm in length, is surrounded by a halo of lustrous and translucent, faintly yellow calcite crystals to 1 cm. The danburite, which is limpid and super gemmy at the termination, exhibits a rich pink color (quite rare from Charcas). THIS IS A SUPERB miniature of way higher than normal quality, and just has a "sparkle" to it that so few possess. It seems a premium price for a "single danburite" and it is, indeed, a relatively high price for a smaller danburite specimen. But it is worth it, in my book
ex. Richard Heck
Rare old material, from one of the few places where you get copper in calcite! This matrix specimen features glassy and gemmy, mostly colorless crystals of "nail head spar" calcite, to 2.5 cm in length, which has grown on top of dendritic copper. Some of the copper is invested with an exquisite greenish malachite patina. In a few cases the copper has actually included the calcite, giving the latter a pinkish glow. The calcite fluoresces a beautiful rich orange color, as a bonus. One or two calcite crystals exhibit damage at their terminations but that does not impact the specimen negatively, and it is a relatively large example for this style. They were said to have been found in the 1950s or before, and we have seen few for sale over the years.
ex. Richard Heck
A rare combo specimen! Perched aestheically on matrix are four tabular, glassy and gemmy, bright orange-colored, wulfenite crystals, to 1 cm across. Associated with the wulfenite are small clusters of rhombohedral, white calcite that have a green coating of pyromorphite - rare for the locale. A super,combo specimen!
ex. Richard Heck
Perched high on an ocherous limonite, are three JEWEL-like crystals of glassy and gemmy, colorless calcite. The largest calcite crystal measures 2.5 cm across. There is also a thin druse of sparkling calcite crystals which enhance the specimen's beauty. Overall, just a gorgeous specimen - NOT a common calcite!
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