|Amber with bugs.
I picked this piece of amber out of literally thousands available at a big fossil show because it was really big, really cheap, and it had bugs in it. It's important to have bugs in your amber if you want to extract DNA and recreate dinosaurs, or impress the kids. I'm told that given the low cost this is probably "copal", not true amber, but hey, it's got bugs in it. Copal is much younger, only a few thousand years rather than potentially millions of years.
And it does have some really great bugs! Here's a close-up of one, which is about 1/4 inch in overall size:
I don't really know what the chemical composition of amber/copal is, but it's an organic resin which means it must contain carbon and hydrogen, and I figure it probably contains at least some oxygen, so I've listed it as being composed of those three elements, with carbon being the dominant one. Feel free to correct me if you know better.
In preparation for my coffee table book The Elements, I had my assistant Nick re-photograph this sample to my new, higher standards. Naturally it fell of the stand and broke into several pieces, which you can see here:
Source: Time Trips
Contributor: Theodore Gray
Acquired: 29 March, 2003
Text Updated: 9 April, 2009