Spectacular Gem Crystals: Pegmatite Pocket Formation and Survival
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- Опубліковано 6 вер 2024
- Presented by Tom Campbell, Staff Mineralogist, The Arkenstone.
In addition to being the Staff Mineralogist for The Arkenstone, Tom is also an independent exploration consultant for the gold mining
industry. He has a passion for and research interest in
granite pegmatites and specializes in their geology and
mineralogy. Much of his mineral collection is devoted to
common and rare mineral species originating from
lithium-cesium-tantalum type granite pegmatites. Tom
has spent considerable time studying and appreciating
the mineralogy of Brazilian pegmatites as well as those
from his home state of South Dakota. During his research
on granite pegmatites he discovered three new minerals:
tiptopite, fransoletite, and pahasapaite and co-described
eight other species new to science. Tom also co-authored the second
edition of the Encyclopedia of Minerals with Bill Roberts and George Rapp, Jr and has published numerous papers in professional journals.
Mineral specimens from gem-bearing pegmatites represent some of the most profound display pieces in both private and public collections with the finest pieces constituting natural art and investments.
What some collectors and the general public may not appreciate is how uncommon single gem crystals and combination specimens containing tourmaline, aquamarine, morganite, topaz and yes, rare species such as amblygonite, herderite, beryllonite, petalite and others actually are!
When we see them on display we tend to take their beauty for granted and sometimes forget about the complex journey they have made to make it to their final destination. This journey includes the complexity of their evolution from granite melts, miarolitic cavity (pocket) formation, the process of gem crystal growth, not to mention their survival in the Earth’s crust for many millions to sometimes over a billion years! And then there is the excitement of discovery and the fastidious extraction process which makes us appreciate how wondrous these gem crystals truly are! Tom Campbell will bring many beautiful and fascinating mineral specimens to this presentation, for attendees to look at and for him to talk about.
Very informative!! Thank you!
Excellent talk! Anybody that owns a 9 cm wodginite has my respect.
I have been to Stak Nala (properly Toghla) in 1999 and 2000. The pegmatite was about 1000 feet long and probably up to 10 to 15 feet thick. There was a distinct horizontal pocket horizon with basketball sized pockets about 2 to 3 feet apart. The pegmatite was swiss cheezed with tunnels up to 50 feet long separated by unmined rock about 2 feet thick. There were other pegmatites in the area and on the valley walls one could see sinuous masses of light colored rock.
Beartooths had (and may still have) some telephone pole sized beryls
Fantastic presentation of incredibly specialized knowledge and experience. Who could possibly give this a thumbs down? Trolls are truly everywhere,, with no hope of them ever going away. Thanks to everyone involved for producing this.
Thank you for posting this, I found it very interesting and educational. I have been wanting to learn more about the geology of pegmatites and this was wonderfully presented.
Glad it was helpful!
Extremely informative lecture. I wish I could pick his brain about some things.
Very informative, interesting & intriguing vid. Planning to go to Pakistan & will definitely checkout the Shingar & Skardu valley pegmatites in Northern Pakistan. Thanks Mr. Campbell for sharing i learned a lot from this lecture.
Wonderful information.
The Himalaya pegmatite of the San Diego area is totally amazing.
Can one of you rock people explain in layman's terms why the more fractionated later stage pegmatites are farther from the parent granite body? Does this imply that the granite is cooling fr the inside out? I'm imagining fractionation occuring as certain elements more prone to crystallization start dropping out of the melt as it cools
At 21:17 and 22:15 you can see that as the melt moves away from the granite (via fractures) it’s solidified/crystalized minerals are left behind.
Hello mr. Campbell I have found one of those pocket of+ + + hoping we could get together so you can work with me on the pocket* my volcano Discovery
Right
;-)