Luanee Posted April 4, 2014 Share Posted April 4, 2014 Hey everybody! New here. I needed help with this, and I thought this looked like the best place to go. I found this chunk of coral in the gravel at the edge Middle Fork of the Vermillion River in Vermillion County in Illinois. I hadn't ever seen anything like it before. I cleaned it up a bit (just water, no chemicals). The top edge is worn from the river, but many of the tiny crystals are in good shape. It is about 8 cm long, and the longest crystals are maybe 1-1.5 mm long. The pictures don't really do it justice- it sparkles like crazy. If anyone could ID the species/time period/rock layer I would be grateful. I don't know much about geology. Is it normal for crystals to grow in coral this way? What tests can I do to figure out what kind of crystal it is? If there is other information/photographs I can provide, please let me know! Thanks! Link to comment Share on other sites More sharing options...
Auspex Posted April 4, 2014 Share Posted April 4, 2014 It is a spectacular specimen, but a solid ID is going to be elusive. Some kind of colonial rugose coral, me thinks, but it is so crystallized that salient details are long gone. Just as well, IMHO, because it would not be so awesome without the crystallization! "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Luanee Posted April 4, 2014 Author Share Posted April 4, 2014 Alright, thank you! I found it while looking for arrowheads. I'll have to keep an eye out for these sorts of things in the future. Link to comment Share on other sites More sharing options...
Coco Posted April 4, 2014 Share Posted April 4, 2014 Hi, I think it is quartz Inside. Coco ---------------------- OUTIL POUR MESURER VOS FOSSILES : ici Ma bibliothèque PDF 1 (Poissons et sélaciens récents & fossiles) : ici Ma bibliothèque PDF 2 (Animaux vivants - sans poissons ni sélaciens) : ici Mâchoires sélaciennes récentes : ici Hétérodontiques et sélaciens : ici Oeufs sélaciens récents : ici Otolithes de poissons récents ! ici Un Greg... Link to comment Share on other sites More sharing options...
Herb Posted April 4, 2014 Share Posted April 4, 2014 Very pretty! But the replacement is so complete the ID is not likely. "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks Link to comment Share on other sites More sharing options...
BobWill Posted April 4, 2014 Share Posted April 4, 2014 Coco is probably right with quartz but calcite is another possibility. Calcite can be easily scratched with a needle or pcoketknife whereas quartz will scratch steel. Link to comment Share on other sites More sharing options...
Coco Posted April 4, 2014 Share Posted April 4, 2014 Could be calcite, but I told quartz due of the shape of certain crystals, and because there is no track of cleavage (when the calcite breaks, it has plans of cleavage, but not in quartz) Coco ---------------------- OUTIL POUR MESURER VOS FOSSILES : ici Ma bibliothèque PDF 1 (Poissons et sélaciens récents & fossiles) : ici Ma bibliothèque PDF 2 (Animaux vivants - sans poissons ni sélaciens) : ici Mâchoires sélaciennes récentes : ici Hétérodontiques et sélaciens : ici Oeufs sélaciens récents : ici Otolithes de poissons récents ! ici Un Greg... Link to comment Share on other sites More sharing options...
Luanee Posted April 5, 2014 Author Share Posted April 5, 2014 Thanks everybody for the responses! I did some googling and I think Coco is right, the crystal shape is definitely more quartz-like. I have seen some calcite crystallized coral, and it looked pretty different. Thank you all for the help! I'll be saving this chunk Link to comment Share on other sites More sharing options...
Pumpkinhead Posted July 22, 2015 Share Posted July 22, 2015 looks like a silicified pleurodictyum to me Link to comment Share on other sites More sharing options...
verydeadthings Posted July 23, 2015 Share Posted July 23, 2015 Looks like quartz to me. In addition to being harder, quartz is easy to distinguish from calcite by the lack of reaction to acid. Calcite will fizz when exposed to acid...scratch a crystal a bit and pour any kind of acid, vinegar from the kitchen works fine, if it doesn't fizz it's not calcite. Very pretty! It's quite rare to get crystals that big in silicified coral, at least in my limited experience Link to comment Share on other sites More sharing options...
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