jamesp
Cave Dweller
Member since October 2012
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Post by jamesp on May 18, 2020 3:52:30 GMT -5
That's right. Almost every piece of silicified coral from Florida/Georgia shows a 'print' on chipped faces, weather worn faces, tumbled faces. The pattern is the polyp/corallite/tube structure and is sophisticated and repetitive. Since most coral is like wood in having vertical parallel structure (tubes verses grain) the pattern shown is dependent of the angle it is cut or broken. Since silicified coral is a staple for making artifacts identification is easy; the artifact will almost always have these 'fingerprints'. Here is an example. Glare is used to show the fingerprint. This sample is ready for pre-polish in a rock tumbler. Even when highly polished the pattern is visible. This would be sawn or broken parallel to the tubes. If it were sawn across the tubes a hexagon pattern would be present. Not sure if the structure is frosted or the chalcedony fill is frosted. My guess would be the structure has the less polished surface and the chalcedony fill is the better reflector. Wow, check out this fingerprint ! Almost every piece of coral from Ga/Fl has this pattern ! Notice how the black 'chemical' has travelled down some of the capillaries(or inverse of the silicified fill or capillaries ?) Closer in at different view angles: The less reflective zones are somewhat permeable and allow chemical intrusion which stains the 'petrified' coral. Coral structure is nothing but a bunch of capillaries anyway. So even after silicification the capillaries (or the opposite of the capillaries ?) pass coloring agents like metal salts thru the capillaries or inverse thereof. In most cases the colored(stained) areas are quite a masterpiece when viewed under magnification - similar to dot coloration on paper. Unfortunately the exotic micro patterns are too small for the eye to see.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on May 18, 2020 4:02:12 GMT -5
This is an example cut across the coral tubes yielding hex corallite/polyp structure. This silicified coral is one of the both toughest and hardest silica rocks known. Super slow to tumble shape. After being tumbled with 500 grit: A pretty metal salt has absorbed into some of the porous fingerprints: Faint patterns still visible after heavy polish, much more vivid if proper lighting was used: These 'sawn across the tubes' slabs would show the same patterns in glare Polished rare Tangerine coral show silica fills And all the well silicified sections of the coral in this wall would yield the same patterns. Zephyr Hills Florida, extreme southern range of silicified coral:
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on May 19, 2020 2:08:46 GMT -5
Cool, thanks for such an informative post on coral from that area. I have some fossil coral i’ve no idea where it came from that I will need to take a close look at. Is all the coral found on the beaches? Most of this shallow water coral was formed in 0 - 20 foot depth of water in a more recent ancient ocean that was about 100 feet higher than the present ocean. The brown sections of the map is where it is most commonly found in peninsular Florida and south Georgia. And the beaches and bays around Tampa About a 250 mile range from Valdosta Ga to Tampa Fl. It all has this fingerprint.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on May 19, 2020 5:25:45 GMT -5
This one out of tumbler yesterday: Tubes at about a 45 degree angle at glare location: Investigation discovery. Rocks busted by their polyp prints. I have found arrowheads 400 miles north of coral sources up here in Atlanta that were ID'ed to be coral.
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