Interesting to see your post on the Meagher formation. I, as you know, just had a brief FB conversation with Rob Thomas on his FB page regarding LaHood formation rocks with my focus on the northern Tobacco Root mountains. Although I was mostly commenting on the LaHood rocks I did slip in that I had been working on Meagher formation mineralized rocks at the time. Because we were focusing on possible mineralized zones I was unaware of any oolitic zones in the Meagher and that is pretty cool and I'm sorry I missed them.
Kind of off topic but I got into a disputed conversation (online of course) with someone that wanted to dispute that ooids were formed by direct precipitation of calcite from seawater. He continued to pronounce that that was impossible because waters were "acidic" (or some other crazy reason which I have purged from memory to protect my sanity). He obviously ignored that we were discussing seawater and refused to believe that you could see this process happening in the Caribbean ocean and the white "sands" on Caribbean beaches were mostly ooids. Well I learned my lesson (mostly) and limit my discussions with sane people.
I also try to limit my discussions to sane people. Challenging sometimes! I think the oolitic facies in the Meagher was one of the hosts for at least some of the mineralization at the Mayflower Mine - at least, that's what I said in my talk at the MBMG mineral symposium in 2017. Based I think on Cocker, 1993, J. Chem. Expl. I don't recall seeing any Meagher oolite on the dumps though - but that was in 1971. The best examples I recall of the middle Meagher oolite were on the order of only 4-6 meters thick, so it's easy to miss even if present (and I suspect it is variable just as the original shoals were).
There’s a guy here on Substack that has a “theory” that layering in sedimentary rocks is actually rows of bricks that have melted, literally that people built all these layers of rock with bricks back in the day. Something to do with Young Earth theory I think? It took me a long time to decide if he was being serious or just really committed to a troll shtick
Mark Cocker was my exploration partner when we were doing our Mayflower mine evaluation. He later was able to do some coring at the mine but I had started dong work in Wyoming and Idaho. I did visit the mine while the drilling was underway and there was some good looking core but the thought was that the contract mining company had gotten most of the good ore (circa late 1940s and early 1950s) just before the mine closed. And they left no records about where they did most of their mining, of course. All of this was caught up in the collapse of metal prices and the ultimate lay-offs of most of the Anaconda exploration staff. Reopening an old mine is expensive and management decided it not a project that they wanted to pursue.
If you have a PDF or even the abstract of the 1993 paper I would love a copy.
Learned something new. The "swash zone" of a shoreline. A few years ago in summer on Lake Michigan, I snorkeled along the edge of the lake in about 1 foot of water, looking for 'cool rocks.'. Hoping to find something that might have micros inside. I noticed that where the waves crashed, the rocks were clean and fresh looking, but in a mere 2' of water, they were mossy and obscured by fibrous growths growing on them, aw-- the waves scour only a very narrow band of shoreline then.
I don't remember if I found much that day, but I has beach goers wondering what in hades I was doing, lol
That outcrop at Newlan Res looks familiar. I scrolled back to a cell phone pic taken on a cold, rainy day in late September 2023, capturing the cut above the southeastern end of the dam, from the northwest end of the dam. Didn't recognize the uncomformity but will return in July 2025 to lay hands on it. Thanks for another enjoyable post!
Nice post Richard. I like looking for interesting minerals in contact zones here in Victoria. You never know what you might come across. Cordierite is, as you say, common, but not easy to find as an aesthetic specimen.
I'm not at all sure I'm a sane person in the sense mentioned above, but I'm a learner and these posts are fascinating to me. In the stratified layers of my knowledge- layed down over seven decades, when I focussed at various times on specific topics intensively, a new layer of geological knowledge is now slowly forming, grain by grain. This essay on spotted rocks was very interesting and adds to the layer (still very thin)! Hurray for lifelong learning and lifelong teachers!
Thanks! Of course any time you feel that one happens to be 'Montana enough,' feel free to share on the Montana Geology FB page - I mostly leave that call to you. And thank you!
The “spots” you referenced in the schistose metapelites are called porphyroblasts in geological lexicon . Albite (as you identified above ) porphyroblasts are ubiquitous in many classifications of schistose rocks .
Interesting to see your post on the Meagher formation. I, as you know, just had a brief FB conversation with Rob Thomas on his FB page regarding LaHood formation rocks with my focus on the northern Tobacco Root mountains. Although I was mostly commenting on the LaHood rocks I did slip in that I had been working on Meagher formation mineralized rocks at the time. Because we were focusing on possible mineralized zones I was unaware of any oolitic zones in the Meagher and that is pretty cool and I'm sorry I missed them.
Kind of off topic but I got into a disputed conversation (online of course) with someone that wanted to dispute that ooids were formed by direct precipitation of calcite from seawater. He continued to pronounce that that was impossible because waters were "acidic" (or some other crazy reason which I have purged from memory to protect my sanity). He obviously ignored that we were discussing seawater and refused to believe that you could see this process happening in the Caribbean ocean and the white "sands" on Caribbean beaches were mostly ooids. Well I learned my lesson (mostly) and limit my discussions with sane people.
I also try to limit my discussions to sane people. Challenging sometimes! I think the oolitic facies in the Meagher was one of the hosts for at least some of the mineralization at the Mayflower Mine - at least, that's what I said in my talk at the MBMG mineral symposium in 2017. Based I think on Cocker, 1993, J. Chem. Expl. I don't recall seeing any Meagher oolite on the dumps though - but that was in 1971. The best examples I recall of the middle Meagher oolite were on the order of only 4-6 meters thick, so it's easy to miss even if present (and I suspect it is variable just as the original shoals were).
There’s a guy here on Substack that has a “theory” that layering in sedimentary rocks is actually rows of bricks that have melted, literally that people built all these layers of rock with bricks back in the day. Something to do with Young Earth theory I think? It took me a long time to decide if he was being serious or just really committed to a troll shtick
I fear that either way, it wouldn't have taken me very long to decide to just move on :)
Mark Cocker was my exploration partner when we were doing our Mayflower mine evaluation. He later was able to do some coring at the mine but I had started dong work in Wyoming and Idaho. I did visit the mine while the drilling was underway and there was some good looking core but the thought was that the contract mining company had gotten most of the good ore (circa late 1940s and early 1950s) just before the mine closed. And they left no records about where they did most of their mining, of course. All of this was caught up in the collapse of metal prices and the ultimate lay-offs of most of the Anaconda exploration staff. Reopening an old mine is expensive and management decided it not a project that they wanted to pursue.
If you have a PDF or even the abstract of the 1993 paper I would love a copy.
I found the paper, I don't think I can attach PDFs here, so I sent it via Facebook messenger. Not sure if it went through, also sent as email.
Nice. I'll look for the paper.
Learned something new. The "swash zone" of a shoreline. A few years ago in summer on Lake Michigan, I snorkeled along the edge of the lake in about 1 foot of water, looking for 'cool rocks.'. Hoping to find something that might have micros inside. I noticed that where the waves crashed, the rocks were clean and fresh looking, but in a mere 2' of water, they were mossy and obscured by fibrous growths growing on them, aw-- the waves scour only a very narrow band of shoreline then.
I don't remember if I found much that day, but I has beach goers wondering what in hades I was doing, lol
That outcrop at Newlan Res looks familiar. I scrolled back to a cell phone pic taken on a cold, rainy day in late September 2023, capturing the cut above the southeastern end of the dam, from the northwest end of the dam. Didn't recognize the uncomformity but will return in July 2025 to lay hands on it. Thanks for another enjoyable post!
Nice post Richard. I like looking for interesting minerals in contact zones here in Victoria. You never know what you might come across. Cordierite is, as you say, common, but not easy to find as an aesthetic specimen.
I'm not at all sure I'm a sane person in the sense mentioned above, but I'm a learner and these posts are fascinating to me. In the stratified layers of my knowledge- layed down over seven decades, when I focussed at various times on specific topics intensively, a new layer of geological knowledge is now slowly forming, grain by grain. This essay on spotted rocks was very interesting and adds to the layer (still very thin)! Hurray for lifelong learning and lifelong teachers!
"open to new layers" would probably be one of my definitions of sanity.
Dick, thanks for the great work on these teaching shorts!
Thanks! Of course any time you feel that one happens to be 'Montana enough,' feel free to share on the Montana Geology FB page - I mostly leave that call to you. And thank you!
Please post on the FB page as you see fit!
interesting! thnk you.
The “spots” you referenced in the schistose metapelites are called porphyroblasts in geological lexicon . Albite (as you identified above ) porphyroblasts are ubiquitous in many classifications of schistose rocks .