Fossil questions

It's quite common for the "marrow" of a fossil bone to be filled with crystals. The soft tissue, in this case the marrow rots away long before the bone begins to be replaced with minerals, leaving a hollow inside of the bone. Just as in a geode, this hollow space is over millions of years filled with crystals.

Awesome, I spent all morning looking at threads from the specimen section. I am really obsessed with opals, pet wood, and fossils, and not as much into rocks and minerals. I saw a bunch of Dino bone pics with the crystallized marrow, I guess I should've checked before asking, sorry. I would still like to see more pics Though, so feel free to post them! The bones I found were, fragments from a lot of animals scattered over a patch of small hills, with a bunch of sandstone ledges running through it. I don't think they were Dino bones, but maybe something more recent like camels and horses. I say that because I found several teeth, and comparing them with online pics they look like horse teeth. I found a partial jawbone with two teeth still in it. Based on the broken fragments around it, it looked like it would've been a skull maybe three times bigger than a modern cow. So I was picturing it being a giant camel. The horse teeth I found appear to be opalized, not glossy shiny opal, but it is a duller shade of blue and black. I find a lot of opalized wood that is really glossy inside but has some dryer looking scales of opalized parts on the outside. That's what the teeth appear to be. I also came across a little spot of badly broken decomposed bones in one area. Looking at them I started seeing what looked like broken tooth fragments, they stood out because the enamel seems to mineralize different than the bone. So right away I thought it was part of a big skull but it was in bad shape and there was no way to tell what it had been. As I was leaving I noticed a really odd shaped bone off to the side. Something about it made me think it was part of a jawbone, I went home and was googling pics and I am almost positive it is a mastadon molar. The roots are broken off, but it is the chewing surface and there are little opalized patches of enamel on it still too.

nmchris, we'd love to see pictures! welcome to the forum!

Score!!! James,That's a beauty!!

Those pieces in the flikr link are beautiful. I have never seen corals like that, the few I have found were very drab looking. The bubbles on the pseudomorphs kind of look like the stuff on fire agate. Very cool stuff!