Learning Center What is a mineral?The most common minerals on earth Information for Educators Mindat Articles The Elements The Rock H. Currier Digital Library Geologic Time

Minerals by Properties Minerals by Chemistry Advanced Locality Search Random Mineral Random Locality Search by minID Localities Near Me Search Articles Search Glossary More Search Options

The Mindat Manual Add a New Photo Rate Photos Locality Edit Report Coordinate Completion Report Add Glossary Item

Mining Companies Statistics Users Mineral Museums Clubs & Organizations Mineral Shows & Events The Mindat Directory Device Settings The Mineral Quiz

Photo Search Photo Galleries Search by Color New Photos Today New Photos Yesterday Members' Photo Galleries Past Photo of the Day Gallery Photography

Discussions

💬 Home 🔎 Search 📅 Latest

╳Discussions

💬 Home 🔎 Search 📅 Latest

Groups

Recent Images in Discussions

Minerals

11th Dec 2010 01:58 UTCReiner Mielke Expert

Is this the largest uraninite crystal ever found?

11th Dec 2010 02:13 UTCAndrew Ferguson

Contact Cliff Trebilcock, Maine/new Mexico

11th Dec 2010 04:09 UTCClifford Trebilcock

Hi Reiner,

I have collected and supplied Uraninite crystals from Topsham,Maine since 1956 to collecters and museums worldwide. As far as I know the

largest Uraninite crystals known were from Ontario. But I have no specifics on size. The finest Quality Uraninite crystals have come from the Swamp Quarry #1 Topsham,Sagadahoc Co.Maine the location I discovered. The largest I found was a little over 5 CM in size.

Cliff

11th Dec 2010 06:05 UTCRock Currier Expert

Reiner

The Handbook of Mineralogy says that Uraninite are as large as 11cm but it does not say where they are from, but the 11cm is a match for the one in the article you reference, so it may be the largest that has yet been recorded in the literature.

11th Dec 2010 14:34 UTCReiner Mielke Expert

Hello Rock,

I think you are right, that the 11cms refers to this specimen. If you would like to incorporate that into mindat somehow? the reference is: University of Toronto Studies, Geological Series, No.52 Contributions to Canadian Mineralogy, 1947, Page 90-91, University of Toronto Press 1948.

11th Dec 2010 15:13 UTCReiner Mielke Expert

While on this subject, A couple weeks ago I was looking at a large crystal I have and it suddenly occurred to me that maybe I was looking at a twin http://www.mindat.org/photo-288457.html. I measured the angles and sure enough it is ( I know it looks obvious but I wasn't expecting to find something like that from there). Anyway it occurred to me that this may be the worlds largest twin ( It is 3.8x3.5x3 cm). What do you think?

4th Oct 2014 13:41 UTCReiner Mielke Expert

Has anyone done a chemical analysis of the Topsham, Sagadahoc County, Maine, USA uraninites? I am paticularly intetrested in the U/Th ratio.

4th Oct 2014 15:38 UTCFred E. Davis

Hi Reiner,

I have data from semi-quant, standardless XRF (thus not exact, but a general idea) for a uraninite xtal from Swamp #1 that shows U:Th (wt% oxide) about 15.2:1.

Fred

4th Oct 2014 16:33 UTCReiner Mielke Expert

Thanks Fred! Would you say this is typical for these?

4th Oct 2014 16:36 UTCFred E. Davis

With n=1, I obviously cannot say it's typical! I was hoping to find more published data, but found nothing specifically for Topsham uraninite.

4th Oct 2014 18:53 UTCLuís Martins 🌟

I think the biggest uraninite crystal is from Fuenteovejuna, Spain. In Dr. Gramaccioli book about radioactive minerals he describes the largest crystal as a 15 cm on edge cube (will need to confirm the exact value, but i think is near that value).

4th Oct 2014 23:15 UTCRock Currier Expert

Many years ago I gave Dem Pohl a small crystal from the Swamp No. 1 Quarry, Topsham, Sagadahoc Co., Maine, USA when he was still working for Exon corp. He said the lab tested it and it was nearly pure end member uraninite.

4th Oct 2014 23:34 UTCFred E. Davis

This is the specimen analyzed, 12 x 10 x 5 mm.

4th Oct 2014 23:49 UTCReiner Mielke Expert

Thats good to know. I am trying to determine if you can distinquish Thorianite from Uraninite using powder XRD. I realize when the Th/U ratio gets close to 1.0 that will not be possible however I have noticed that the peak at 85 2-Theta has a very pronounced shift to higher values with increased U content. In fact it appears to shift by about 4 degrees 2-theta from Madagascar Thorianite to Swamp Uraninite the greatest shift of all the peaks. Assuming a linear relationship exists between increasing 2-Theta and U content one should be able to distinguish Thorianite from Uraninite using this peak in some cases. Any thoughts on this?

By the way awsome crystal Fred!

5th Oct 2014 00:12 UTCFred E. Davis

Thanks, Reiner! The stunning luster made it difficult to photograph. Of the uraninite specimens I've collected and examined, the "cleanest" uraninite with the least amount of Th is from McKinney mine, Spruce Pine, NC (U:Th ~164:1); the highest Th content I've found (a very lucky find - it's the first and only uraninite reported for the locality) is from Jail Hill quarry, Haddam, CT (U:Th ~5.5:1).

5th Oct 2014 02:08 UTCRudy Bolona Expert

There's an old report of a uraninite crystal of 7 inches on edge, almost 18 cm and weighing 25 lbs! from Mica Basin in Routt County, Colorado. Where this specimen ended up, who knows? I went to this locality, but had no such luck in finding the exact spot. The area is huge! Could this be the largest U.S. uraninite?

Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: May 10, 2024 02:01:16

Go to top of page