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Posted by Rob Woodside  
Rob Woodside June 17, 2009 06:11PM
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.

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 |Si2O7> 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.

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)

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.

Edited 3 time(s). Last edit at 07/26/2010 09:41AM by Rock Currier.
Rock Currier June 17, 2009 08:48PM
Bob, thats a good start. Now go and do 500 more.

Rock Currier
Crystals not pistols.
Tony Peterson June 17, 2009 09:56PM
ok just some brief comments on my photo......the specimen is indeed from a trench in the Bond Zone i visited there on a GSC field trip eons ago and i'm not sure why i entered the wrong locality but it's been fixed. that specimen id has been confirmed by sem-eds, good niocalite for sure. and i've been meaning to upgrade the photo as this is the FIRST closeup shot i ever took holy moly, i'll move that up the list. stop.
Rob Woodside June 17, 2009 10:10PM
Thanks Tony. The Oka apatites were more brown than yellow. What made your apatites greyish? Did you EDS the apatites? (Ca,OH)???

Edited 1 time(s). Last edit at 06/17/2009 10:15PM by Rob Woodside.
Etienne Medard August 16, 2009 06:05PM
About the niocalite/apatite issue : niocalite is tetragonal, apatite hexagonal. This is quite distinctive on the specimens I have from Oka.

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