http://www.mindat.org/msgboard-80.html Sun, 26 May 2013 05:32:56 +0000 Phorum 5.2.15a http://www.mindat.org/forum.php?read,80,144105,144105#msg-144105 http://www.mindat.org/forum.php?read,80,144105,144105#msg-144105 Best Minerals N and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.



Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?



Nobleite
CaB₆O₉(OH)₂·3H₂O Monoclinic

1.Nobleite on Colemanite ~12cm wide	©

Nobleite is a fairly rare borate mineral and Mindat currently lists 8 localities for the mineral. The only one of note is the Corkscrew mine in Death Valley, California where crystals up to about 3mm have been found. It is sometimes found as mammillary post mine coatings.The mineral is also found in small amounts at a few other borate deposits, and if you looked carefully you would probably find it at many localities where Colemanite and other calcium borate minerals are found.
[Rock Currier 2009]


Nobleite
USA
California, Inyo Co., Death Valley, Furnace Creek District, Corkscrew Canyon, Corkscrew mine

2.Nobleite on Colemanite ~10cm wide	©

3.Nobleite on Colemanite FOV 2.4cm wide	© Caltech

4.Nobleite crystals FOV 5mm	© Don Volkman 01/06

The Nobleite find at the corkscrew mine was a one time thing, although undoubtedly somewhere in the mine more exist. They were all found growing on drusy tray/tan Colemanite crystals. The find consisted of perhaps two or three hundred specimen, two of the best know are in pictures 1 & 2 above. They were found by a man named Denis Sutherland and I don't think he told anyone exactly where in the mine they came from, but the matrix they grew on and the matrix matched exactly know Colemanite specimens from the mine and though no one has found more in the mine I feel certain that they are from there. He used these to trade specimens from all over the world to add to his collection. When his collection was sold the fine specimens shown here were in that collection. There are literally thousands of pockets of Colemanite in the mine and once you collect there you can understand how a collector might be able to find a pocket the size of a small refrigerator that all other collectors had overlooked before.

The Corkscrew mine is a small mine that has produced a few thousand tons of Colemanite ore, but it is a small mine as mines go but is one that some day should be turned into a tourist attraction because everywhere you look are sparkling pockets of drusy Colemanite. You used to be able to just drive up to the mine and collect as many pounds of specimens as you wanted, but the problem was that when you got home there was not much you could do with them. They were so common that no one wanted them very much, and if they did want some they could go and collect all they wanted as well. All the collectors in the Los Angeles area has specimens from the mine. You didn't even have to move much rock when you were collecting. You could just go around the mine and pick up specimens discarded by collectors looking for better specimens. Today, the road to the mine is gated and there is a heavy steel door on the mine. Someday if the Park Service that oversees Death Valley ever manage to get the mine from the Mining company they could turn it into a dandy Tourist attraction.
[Rock Currier 2009]



Click here to view Best Minerals N and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.]]> Rock Currier Best Minerals N Mon, 06 Jul 2009 09:07:44 +0000 http://www.mindat.org/forum.php?read,80,141944,141944#msg-141944 http://www.mindat.org/forum.php?read,80,141944,141944#msg-141944 Best Minerals N and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.


Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

Below are some preliminary notes I have made about Niocalite. This entry and thread has been made as a place holder for information that you will hopefully contribute about Niocalite. It should be in no way be thought of as a claim I have staked out to write about this mineral, and in fact is an invitation for someone to step forward and create the article about this mineral. If you are so inclined and have questions about the format that such an article should have, go the The welcome topic at the top of the Best Minerals forum and read what has been posted there. Also take a look at some of the more mature articles that have already been written like Rhodochrosite, Adamite, Millerite etc. You will need also to pick out other images of Niocalite that will go into the article.


Niocalite Rare Mineral and Species Collections
(Ca,Nb)₄[(O,OH,F)₂ |Si₂O_7] Monoclinic

Niocalite (yellow) from the Nb-rich sovite at Oka, Quebec. Largest crystal is approximately 4 mm long. Also present are calcite, perovskite (black) and apatite (grey, corroded by weak acids). Contrast has been digitally enhanced to distinguish the calcite matrix from the niocalite, which is actually a slightly paler yellow. Tony Peterson collection.	© Tony Peterson

The niocalites resembled the apatites and one had to be careful identifying them. (well, they are quite yellow, and should you be lucky enough to see terminations, that would clinch it)

In fact I have my doubts about some of the niocalite photos here. (Peterson's photo 46987 is the most convincing)

Laszlo Horvath who lives close to Oka set up the localities and species listed here. He did not list the St Lawrence Mine as a niocalite locality. (that would be correct, niocalite has never been reported from the St Lawrence Mine)

Old folklore was that Niocalite occured throughout the complex. (no, it only occurs in a single rock layer within the Bond Zone (which is in the SW part of the complex)

That is reflected in the two localities listed here for Niocalite- the Bond Zone and the whole Oka Complex!!! What to do? (well, the general occurrence of "Oka Complex" can be dropped. The trenches exposing niocalite-bearing rock are only on the Quebec Columbium Ltd property, so the general locality for any niocalite for which a specific trench number is not known can read: Quebec Columbium Ltd property (Bond Zone), Oka Carbonatite Complex, Deux-Montagnes County, Quebec, Canada. The Complex has also been referred to less frequently as the Oka Alkaline Complex)

Cheers,
Bob Ramik

Also, nearby the type latrappite is the type niocalite occurrence at lat/long: 45.5020, -74.0504 . This is the west end of trench T4 of the Quebec Columbium Ltd property. Niocalite came from other nearby trenches that also exposed the same niocalite-bearing rock in the Bond Zone, but the best (and probably most) specimens of niocalite came from T4.



Click here to view Best Minerals N and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.]]> Rob Woodside Best Minerals N Sun, 16 Aug 2009 18:05:39 +0000 http://www.mindat.org/forum.php?read,80,129406,129406#msg-129406 http://www.mindat.org/forum.php?read,80,129406,129406#msg-129406
Ideally what we want to know about each significant mineral from each locality is:

1. What is the largest crystal of the mineral that the locality has produced?
2. What do the best specimens from this locality look like and where can one be seen?
3. Does the locality produce a variety of different kinds of specimens of this species, and what do the best of each type look like and how many of them were found etc.
4. What are the associated minerals found with this species and what is its geological setting?
5. How abundant are these specimens and when were they found? A type locality? In other words, how rare are they.
6. How do they compare to other specimens of the same mineral from other localities?
7. How much is it worth. This should probably be optional, but in cases where specimens are worth thousands of dollars we should probably say something of the value of these things.
8. What kind of care and feeding do these specimens require? Are they delicate, radioactive, unstable, color changeable etc.?
9. Are the specimens commonly faked, and if so, how to tell if they are?
10. Are there any interesting stories relating to the collecting of these specimens or their discovery as a new mineral?

Of course this is in reality impractical, but if we keep these questions in mind, we will do a lot better job when writing about them.]]> Rock Currier Best Minerals N Fri, 06 Mar 2009 11:21:29 +0000