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Latrappite

Posted by Rock Currier  
avatar Latrappite
June 17, 2009 12:57AM
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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?


Latrappite
(Ca,Na)(Nb,Ti,Fe)O3 Orthorhombic
Latrappite, St Lawrence Columbium Mine, Oka, Deux-Montagnes Co., Québec, Canada 2.5cm tall© Rob Lavinsky


Here will go a general discussion about Latrappite specimens.



Latrappite
Canada
Québec, Deux-Montagnes Co., Oka complex, Oka, St Lawrence Columbium Mine

We need someone to tell us about the locality and its specimens.


Philip, it is possible that some latrappite specimens stated as being from the St. Lawrence Mine are correctly labelled. But it's likely that most if not all specimens came from the type locality, or from near it.

So let me add to the mess, by giving my understanding of the type latrappite - and type niocalite localities. I visited these localities with Duff Gold a couple of times ~1970. Those recollections together with transferring his published sketches onto Google Earth are what I base my comments upon. The type positions should be good to 10-20 meters; I hope to improve on them in person with GPS some day.

Ernie Nickel designated a single type latrappite specimen in 1964. It came from one unspecified trench of a group of at least five trenches on the Columbium Mining Products Ltd property. These trenches exposed the Bond Zone, a niobium-rich zone of the Oka alkalic complex. The midpoint of this group of trenches is at lat/long: 45.5001, -740470 .(see attached map). Now Gold, in his published sketches, and by personal communication, specified a single trench located alongside a small road, as being the "type trench". I did not verify this with Nickel. That trench is at lat/long: 45.4996, -74.0461 . The latrappite could still be readily collected from this exposure in the '70's.

Some further comments. it is not correct to assume that all of the "perovskite mineral" from the Columbium Mining Products property is latrappite. Some was found to be niobium-rich perovskite (analysis by Guy Perrault in 1960). Rob mentioned that the St. Lawrence Mine pits swallowed the Bond zone latrappite occurrence(s). That is not so. The mine pits known as Pit A1 and A2 can seen nearby at 45.501, -74032 and 45.499, -74-030 respectively. In the mine itself, some of the "perovskite" mineral in A2 is rich enough in Nb to warrant being called latrappite.

To finish with "perovskite", I can add that any of the peculiar "perovskite" you may have from the Oka Rare Metals property can be safely labelled perovskite (containing only minor rare earths and with Nb2O5 below 1%).

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.

Cheers,
Bob Ramik
Royal Ontario Museum
Toronto, Canada

Bob Ramik [ PM ]
Re: Latrappite new
June 17, 2009 02:29PM IP/Host: zefram.rom.on.ca
Registered: 1 year ago
Posts: 3
Hi Rob,

I'm happy to help! To answer your questions & concerns:

I visited the property with my Dad in the early sixties and can remember a long slight climb through fields to the trenches. I don't think they were in production then. (they have yet to be exploited)

The folklore at the time was that all the Oka "Perovskites" were Latrappites (definitely not so)

So the Oka Rare Metals property produced only Perovskite, while the St Lawrence pits produced both Latrappite and Niobian Perovskite. (yes)

Did Niobian Perovskites occur in the Bond Zone or were they all sufficiently enriched to be Latrappite? (both are found in the Bond Zone. Perrault analyzed the niobian perovskite from there)

Could I ask you to please upload that photo with the marked type localities into the Oka locality photos? (haven't done this before but I'll try)

Should we change the locality structure here at Mindat to include the Columbium Mining Products property and your coordinates? (I had a look at Mindat, and yes changes are warranted)

From a collector's viewpoint it is disappointing to have another species for which every specimen must be analysed to find the species it contains. (sure is!)

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



Click here to view Best Minerals L and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Rock Currier
Crystals not pistols.



Edited 2 time(s). Last edit at 07/26/2010 09:33AM by Rock Currier.
Re: Latrappite
August 16, 2009 06:09PM
Same comment than on another post, can we find a picture of an analyticaly verified latrappite? Or are we only dealing with Nb-rich perovskites?

Etienne
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