msuwabbit
off to a rocking start
Member since June 2020
Posts: 23
|
Post by msuwabbit on Sept 9, 2021 9:45:18 GMT -5
Good Morning, I went to the Patty quarry last Sunday and picked up some nice rocks. Many of the agates had a crystaline crust, similar to the interior of a geode. Some had a botryoidal appearance like malachite, encrusting a chert substrate. The botryoidal layers ranged from pinks, reds, amethyst purple, and blue. Can anyone educate me on what these types of crystals are called, and if any of you have had success in polishing them. Thanks, David
|
|
|
Post by rmf on Sept 9, 2021 16:09:25 GMT -5
msuwabbit Image 1 & 3 look like typical Summerville aka GA lace Agate. Not sure where Patty quarry is though. The crystals are quartz. The agate polishes nicely BUT... The agate tends to have vugs which cause a lot of trouble when tumbling. You have to make sure the grit is out or that causes problems with polishing. For cabbing there are also problems. Between the layers there is often a layer of white kaolinite which tends to let go once it has been slabbed and cleaned making it hard to make any cabs over 18x25. Some is hard and solid but I have cut little due to the above problems. On my todo list is soak some slabs in sodium silicate and try to stabilize it but have not tried it yet. Too many other irons in the fire. Pic #3 looks like it might be solid enough to make some nice cabs.
|
|
Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,456
|
Post by Sabre52 on Sept 9, 2021 16:46:53 GMT -5
That last one is incredible and very well agatized. That grape formation in the first example is called botryoidal agate but the second is what I would call a tube agate as the formations are almost like stalactites. I've not had my hands on a lot of Summerville agate but that last one is freaking awesome and likely very rare. I'd either leave it as a specimen or "very carefully" cut or grind, and polish it across the tubes so as to display those wonderful concentric patterns.
|
|
|
Post by jasoninsd on Sept 9, 2021 19:49:13 GMT -5
I'm with Mel...that third piece is an amazing specimen! I'm not sure I could cut that one...but I'd be tempted! That concentric banding makes it look like a Gobstopper conglomerate!
|
|
msuwabbit
off to a rocking start
Member since June 2020
Posts: 23
|
Post by msuwabbit on Sept 10, 2021 9:07:26 GMT -5
Guys, #3 isn't even among the best looking ones we found. I have some beauties. We are going back next month.
|
|
|
Post by jasoninsd on Sept 18, 2021 20:10:05 GMT -5
So, I got a surprise box at my front gate this afternoon! Super special thank you to msuwabbit ! This is the first time I've seen this type of agate. It reminds me of a seam agate. Being the material "hoarder" that I am, I have a tendency to cut material to get the most slabs/slabettes out of it. However, I learned a cool lesson with this material. If it's cut parallel to the botryoidal pockets, it produces some amazing patterns! Pic 1-2: These cuts were made down through the botryoidal pocket. These seem to be pretty stable. Pic 3: Cutting them this way leads to the following patterns. Pic 4: Cutting it per pic 3 lead to some instability in some of the cuts. Pic 5-7: These were the patterns produced cutting parallel! I like both types of patterns! I'm excited to see how these cab.. although rmf has me nervous! LOL
|
|
JR8675309
freely admits to licking rocks
Member since August 2019
Posts: 751
|
Post by JR8675309 on Sept 18, 2021 21:18:08 GMT -5
KILLER!
|
|
msuwabbit
off to a rocking start
Member since June 2020
Posts: 23
|
Post by msuwabbit on Sept 20, 2021 12:47:35 GMT -5
Awesome! I look forward to seeing the cabs.
|
|
|
Post by jasoninsd on Sept 30, 2021 19:51:21 GMT -5
Okay...so I learned this material can put a smile on someone's face, or it can be super depressing! I don't know the technical jargon to use...I think it may have something to do with the silica content in this agate...but it seems to be a very hit it miss material. I had preforms cut out that looked solid, but when I ground them, all of a sudden pits opened up. It's also a very "soft" material compared to something like a Laguna Lace. If I'm totally guessing, I'd say it was around a Mohs 5. In the first picture, this preform started out as a pretty high dome. I saw pits on the surface, so I kept grinding it down hoping to get below the pits. But they just kept on coming, so I stopped before it got completely flat! In the second picture, this too is a high dome, but no pits showed up. There is a very minute amount of undercutting in a couple of the banding areas...and I mean it's VERY slight. I'm very happy with how this one turned out!
|
|
|
Post by rmf on Oct 1, 2021 8:53:21 GMT -5
jasoninsd You have proven my point. Georgia Lace Agate (aka Summerville Agate) is a cold water agate formed in the ocean bottom. The Agate is not completely solid and some bands are coated with koalinite which tends to cause separation between parallel layers. That is why pieces like the two above are better for cabbing because the complex banding locks in the layers. GLA also forms around local chert. Which in our area contains a lot of gas bubbles. So in the GLA you also get voids that do not polish. When we made our first trip to the Summerville area (43 years ago) it took me about an hour to pickup 200# of GLA. Tumbling was a nightmare. The voids catch grit (especially the coarse) and at the time I was using just rotary tumblers and it is relatively unforgiving about loose coarse grit that falls out of vugs. You basically had to scrub each stone with a tooth brush to get it clean enough for the next grit. Cabbing you get a lot of fracturing or cabs that just fall apart. You also have quartz crystals which polish differently from the agate bands. I have not tried to stabilize GLA but it will be one of my projects for the future. This is why you see few cabs of GLA and the ones you see tend to be smaller. But the one above looks great. When you get solid material they look good.
|
|
|
Post by jasoninsd on Oct 1, 2021 13:42:18 GMT -5
jasoninsd You have proven my point. Georgia Lace Agate (aka Summerville Agate) is a cold water agate formed in the ocean bottom. The Agate is not completely solid and some bands are coated with koalinite which tends to cause separation between parallel layers. That is why pieces like the two above are better for cabbing because the complex banding locks in the layers. GLA also forms around local chert. Which in our area contains a lot of gas bubbles. So in the GLA you also get voids that do not polish. When we made our first trip to the Summerville area (43 years ago) it took me about an hour to pickup 200# of GLA. Tumbling was a nightmare. The voids catch grit (especially the coarse) and at the time I was using just rotary tumblers and it is relatively unforgiving about loose coarse grit that falls out of vugs. You basically had to scrub each stone with a tooth brush to get it clean enough for the next grit. Cabbing you get a lot of fracturing or cabs that just fall apart. You also have quartz crystals which polish differently from the agate bands. I have not tried to stabilize GLA but it will be one of my projects for the future. This is why you see few cabs of GLA and the ones you see tend to be smaller. But the one above looks great. When you get solid material they look good. Okay...THIS was the technical jargon I was looking for! - Thank you for posting this! I wonder if the kaolinite is what caused some of my Laguna Lace to do the same thing...separate rather easily along the fortification layers... Thanks for the compliment on the cab. I was super stoked that one turned out like it did. It gives me hope that there will be more that are just as solid...fingers crossed. I wondered about the stabilization...but pondered whether it would be worth the effort. I think maybe so, because it's gorgeous material. Also thanks for clarifying that Georgia Lace Agate and Summerville Agate are the same material. I've seen a seller putting GLA up for bid on eBay, but no one is biting at it for $20 on a "slim" filled MFRB with free shipping. I've looked at the pieces on there and it looks like each fortification layer is coated with kaolinite....you can see how it fractures that there's no solidity to the banded areas. I can see the value in this material if it's as abundant as it seems...and it's self collected. Definitely worth the effort then...at least in my opinion.
|
|