As I am almost 70, I just can't roam around in rocky terrain like I used to. It's cool to see other people doing that. Wandering around in weathered pegmatite outcrops and/or old mines is like being "a kid in a candy store" or opening birthday presents.
3:10 No, you generally do not find amphiboles (hornblende) or pyroxenes (aside from spodumene of course) in a granitic pegmatite. If it’s a dark mineral like that, it’s generally going to be schorl. This is because of amphibole’s and pyroxene’s place in the Bowen’s reaction series. As pegmatites (especially complex) are generally the last portion of a magma body to cool, much of those minerals higher up in the Bowen’s Reaction Series would have long crystalized within the parental granite. This is especially the case with LCT type pegmatites, which tend to be ultra-evolved and don’t even have biotite (with very few exceptions). You can, however, find biotite more commonly in NYF-type granitic pegmatites. Also minerals like augite and diopside are generally not found in granitic anything, much less a pegmatite. Granites in general are generally too felsic/silica rich for the likes of augite and diopside, which are generally found in more mafic rocks like basalt/gabbro. There have been select few granites which may have that, but it’s very, VERY rare. That which you are currently holding is schorl tourmaline, no hornblende.
As for corundum, there are corundum-bearing pegmatites, *BUT* they’re very rare and generally lack quartz, as corundum and quartz do not mix well geochemically in solution (the silica uses the aluminum that would otherwise make corundum for alumina-silicates like feldspar and mica). I know of a wonderful sapphire-bearing pegmatite in North Carolina from the Old Pressley Sapphire Mine- dominated by Na-plagioclase and muscovite, but no quartz. Oh, there is one highly unusual exception to what I mentioned- and that would be in the form of corundum xenocrysts. Corundum has a very high melting temperature, even higher than basaltic magma would reach. Montana sapphires are said to be from a lamprophyre lava rock, and some of the burmese sapphires are as xenocrysts within basalt. But corundum/sapphire xenocrysts in a granitic melt are *extremely rare*.
First year rockhounder here. I live in an area where everyone says rock hunting is a waste of time. I find so many granitic pegmatites though! And they're all so pretty lol
I live in northern San Diego County. I've read that the best minerals to look out for in this area are pegmatites, but I wasn't sure if I had found them or not. I think that I may have a few times based on the large size of quartz that was in them. I suspect that I've found some with very small tourmalines of black and pink, but I'm not that good of a rock hound yet to be certain that they are tourmalines.
You are using words that I have not used in a long time but I have noticed over the years mountain ranges like the Rockies and the Smokey's are generally comprised of granite and or limestone all that other stuff is just extra 💥😁🐝
That is a lot of it! There are intermediate rocks, like many varieties similar to granite that technically are called something else. And same with limestone-like rocks, the silts and sandstones that look similar sometimes. Those technical differences and names are usually more important to the person intricately studying them. However, hopefully I will over time show how cool they all can be!
Yes, actually quite often. Had a few close calls - one in the sage brush of Montana, one in the mountains with a Mojave Green in California. The others were far enough away to “enjoy” such as some nice diamondbacks and a black tail in Arizona, albeit I sat next to him for a while before realizing he was there sunning, and a nice Massasagua in Washington. The rock hounds scare me more than my own safety, since they poke around without as much caution!
@@LetsGoGeo Yep I may or may not have gone digging at night at a few places held by old stereotypical mountain hillbillies who knew exactly why people wanted there and just stop people for no reason despite not giving a shit about minerals or radiation (the real reason I dig rocks)
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As I am almost 70, I just can't roam around in rocky terrain like I used to. It's cool to see other people doing that. Wandering around in weathered pegmatite outcrops and/or old mines is like being "a kid in a candy store" or opening birthday presents.
كم احب البيغماتيت..
2:54 2:55 2:55
3:06
3:20
3:10 No, you generally do not find amphiboles (hornblende) or pyroxenes (aside from spodumene of course) in a granitic pegmatite. If it’s a dark mineral like that, it’s generally going to be schorl.
This is because of amphibole’s and pyroxene’s place in the Bowen’s reaction series. As pegmatites (especially complex) are generally the last portion of a magma body to cool, much of those minerals higher up in the Bowen’s Reaction Series would have long crystalized within the parental granite. This is especially the case with LCT type pegmatites, which tend to be ultra-evolved and don’t even have biotite (with very few exceptions). You can, however, find biotite more commonly in NYF-type granitic pegmatites.
Also minerals like augite and diopside are generally not found in granitic anything, much less a pegmatite. Granites in general are generally too felsic/silica rich for the likes of augite and diopside, which are generally found in more mafic rocks like basalt/gabbro. There have been select few granites which may have that, but it’s very, VERY rare.
That which you are currently holding is schorl tourmaline, no hornblende.
As for corundum, there are corundum-bearing pegmatites, *BUT* they’re very rare and generally lack quartz, as corundum and quartz do not mix well geochemically in solution (the silica uses the aluminum that would otherwise make corundum for alumina-silicates like feldspar and mica). I know of a wonderful sapphire-bearing pegmatite in North Carolina from the Old Pressley Sapphire Mine- dominated by Na-plagioclase and muscovite, but no quartz.
Oh, there is one highly unusual exception to what I mentioned- and that would be in the form of corundum xenocrysts. Corundum has a very high melting temperature, even higher than basaltic magma would reach. Montana sapphires are said to be from a lamprophyre lava rock, and some of the burmese sapphires are as xenocrysts within basalt. But corundum/sapphire xenocrysts in a granitic melt are *extremely rare*.
First year rockhounder here. I live in an area where everyone says rock hunting is a waste of time. I find so many granitic pegmatites though! And they're all so pretty lol
What part of Arizona is this?
Pegmatites are so fascinating! Love your presentation!
I live in northern San Diego County. I've read that the best minerals to look out for in this area are pegmatites, but I wasn't sure if I had found them or not. I think that I may have a few times based on the large size of quartz that was in them. I suspect that I've found some with very small tourmalines of black and pink, but I'm not that good of a rock hound yet to be certain that they are tourmalines.
Lots of pegmatite here in San Diego
And as many know a famous locality for gem tourmalines and other precious minerals found in pegmatites
I do have one pegmatite in my collection. It’s mainly Muscovite mica interspersed with some pink orthoclase feldspar. I would love to find some more!
Awesome! Yes, these are fun to rockhound. The crystal sizes can be impressive.
We have loads of pegmatite in Maine. Very cool
Im in Australia, never seen mica that size in the wild! Wow!!
Very interesting video. thanks for sharing the study.
Wow a lot of silver on that area
Man! I love rockhounding and we were out last weekend on a pegmatite area, love the vids u got another subber!
Lots of Pegmatites in Australia.
Great video, very informative, thanks, just found your channel & looking forward to watching more
You are using words that I have not used in a long time but I have noticed over the years mountain ranges like the Rockies and the Smokey's are generally comprised of granite and or limestone all that other stuff is just extra 💥😁🐝
That is a lot of it! There are intermediate rocks, like many varieties similar to granite that technically are called something else. And same with limestone-like rocks, the silts and sandstones that look similar sometimes. Those technical differences and names are usually more important to the person intricately studying them. However, hopefully I will over time show how cool they all can be!
Thank you ☺️
Love the explanation
Very informative thank you...
If you can please do lithium
should i open a pegmatite? Try to extract gems? help
Nice video! Where in AZ are you, I would love to take my kids there to try and find something.
Hari Aum Namaste Ji.. Kindly come with your team to dig some minerals here at kullu valley
Good video, subscribed!
Thanks!
Hands down my favorite rock. It's like a box of chocolates...
I like this analogy!
thanks ,,, so superb😘,
@6:20 huge!
Informative but need hand specimen properties explanation.
Do you encounter rattle snakes? I'm sure you clear an area before you go poking around
Yes, actually quite often. Had a few close calls - one in the sage brush of Montana, one in the mountains with a Mojave Green in California. The others were far enough away to “enjoy” such as some nice diamondbacks and a black tail in Arizona, albeit I sat next to him for a while before realizing he was there sunning, and a nice Massasagua in Washington. The rock hounds scare me more than my own safety, since they poke around without as much caution!
great chanel
Pegmatites in Little Switzerland North Carolina has some Autunite in them. I am trying to find a place there that will let me dig.
It is harder to gain access to good dig sites on the east coast. The plethora of public land in the west makes access much easier.
@@LetsGoGeo Yep I may or may not have gone digging at night at a few places held by old stereotypical mountain hillbillies who knew exactly why people wanted there and just stop people for no reason despite not giving a shit about minerals or radiation (the real reason I dig rocks)
Whe you say slow cooling pegmatite can you please say what you mean slow. How slow are we talking ?
very very Nice
I’d like to find some probertite with you.