Identity HelpHelp Identifying locality for red calcite
I am a big collector of US calcite specimens, especially Missouri. When I came across this piece, the hunch was that it is from Missouri, possibly Fletcher Mine. Fletcher had the Red Phantom Pocket in 1998 and the Red Calcite Pocket in 1999. However, I've seen a few red phantoms from Fletcher and the surface characteristics and the depth of the red clay inclusions do not really check out, nor does the twin plane. As far as the Red Calcite Pocket goes, I have not seen as much of that material to be certain.
At the same time, I do not want to narrow my search too much, after all, it may not be from Missouri at all.
Details: 11cm tip to base, 5cm at widest point. There is a twin plane {001}. The red clay inclusions are 1-2mm below the surface. 4/6 of the crystal faces have high luster while two adjacent faces feature microcrystalline scalenohedrons. There are no phantoms within, just the superficial red inclusions. No signs of matrix.
Thanks for your help!
Regards,
Ed Bayley
With calcites from the US Midwest, you have to carefully determine whether the red color (or other shades) is on the surface or is a true part of the crystal. I have several Indiana calcites with shades of orange and red representing surficial iron oxide staining. Some crystals can look so great and aesthetic that you think the shades of color are truly part of the crystal.
Best dip the broken end of the base in vinegar for only (!) 10 - 15 seconds. If iron oxide staining, the color will rapidly change, lightening up a bit without otherwise damaging the crystal itself. CHEERS.......BOB It is definitely trapped just under the surface about 1-2mm under. It also looks like just one layer was deposited rather than concentric layers. I wouldn't want to dip any of it in acid because if it is actually a Fletcher miner piece with a twin plane, it is exceedingly rare. 
I wouldn't it either because after the fact, it's an altered piece. I imagine that looking with a loupe should help see if it is on the surface or not. 
Hi Ed,
It doesn't look like any of the Fletcher Mine calcites that I've seen. The reddish color reminds me of some of the calcites from Chenzhou Prefecture, China, However, I don't recall seeing the color on a scalenohedral crystal quite like yours.
Kevin I traced the base back to Sunnywood and they were able to confirm from records that it is a Missouri specimen, but were not given locality details. So I am happy that at least it is not Chinese, but I agree it does not look like most of what I've seen from the Red Phantom or Red Calcite pockets. Laurence Nuelle was pretty confident that it was from one of the two finds, but wants to see it in person, so I will bring it to Tucson. But looking at it, the shape and size is more like Red Calcite pocket, but the amount of luster seems unusual as well as the micro crystallization on the two etched faces.
