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theropod wrote:Piper,
I forgot to mention the other mechanical option of micro abrasion. Basically a tiny sand blaster these high precision instruments can speedily remove stubborn matrix. Again a skill one must gain by practice. A special chamber must be used to contain the abrasives and stone dust, with gloves like a radiation isolation chamber. Some of the abrasives can be expensive, but for final polishing work food grade baking soda is great.
Again, I recommend one look HERE'S for more info.
RS
The_Piper wrote:theropod wrote:Piper,
I forgot to mention the other mechanical option of micro abrasion. Basically a tiny sand blaster these high precision instruments can speedily remove stubborn matrix. Again a skill one must gain by practice. A special chamber must be used to contain the abrasives and stone dust, with gloves like a radiation isolation chamber. Some of the abrasives can be expensive, but for final polishing work food grade baking soda is great.
Again, I recommend one look HERE'S for more info.
RS
Hi Therapod,
Thanks man, I saw that link and read the whole page. It's very helpful as always. Even has brand recommendations. It got me thinking of looking for Ice Age animals in gravel pits. I might have access to one this summer that my friend is digging up for fill. He said I could go look. For today I think I'm going to put the etching on hold. I really appreciate your help.
There's a real lot to invest in practice and money to do a good job of it I think. I'm still intent on figuring out the acid tests though. I need to get a little piece of definite Limestone so I can watch it fizz with my own eyes.
I'm intent on learning about the fossils and geology right now, and finding more fossils. They're both very enjoyable to me.
I'm not sure if you saw these pics a few pages backhttp://www.rational-skepticism.org/earth-sciences/help-identifying-a-rock-fossil-post-your-finds-t832-60.html#p54243Do you have a guess if those spots are fossil poop or baby sea urchin type animals, or neither? There are more fossils around the rock. I should be able to id the fossils on my own in due time, but if anyone alse wants to look, I'll be happy to share more pics.
In the images you are referencing I what I am seeing is some internal partial replacements. The surrounding rock may have a good representation of the organisms in question, as they appeared (morphologically) before deposition, but you'll be looking at those in negative. I can't tell anything about those without the ability to see the 3D aspects of these molds. I think some people have tried making thin membrane casts and peeling these out after they've cured. These were then used to make a mold to cast replicas in Plaster-of-Paris. Needless to say that's a real pain in the ass.
Primary rock type slate
Secondary rock type sandstone
Tertiary rock type conglomerate; graywacke
An interesting-looking rock. It does not appear to be a fossil. My guess is that you have a rock that was cracked and a vein of other material (guessing, calcite) was inserted. This vein was subsequently itself broken up with a harder mineral, more resistant to erosions (guessing, quartz) inserted into the original vein. The softer (or at least, more easily broken material preferentially breaks out leaving the harder material in relieve, producing the interesting “toothed” effect.
Just my guesses, but such rock histories – rock formation, insertion of a vein, then subsequent breakage and differential erosion – are not unusual.
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