Jump to content

Fossil ID: pyritized wood, mica, something else?


Recommended Posts

Hi there,

I found this specimen on a hike outside of Denver, Colorado. It was laying in the middle of the trail. It’s about 10cm long. It has grain that looks like wood or layers like mica. It’s also gold and shiny like pyrite or mica. It’s layers are wavy and it leaves a gold dust behind when handled. It’s stunning when the light hits it. Hoping to identify what it is.


Thank you!






Link to post
Share on other sites
Bradley Flynn

Hi That is a really nice piece. I have a similar specimen that was identified as schist, search schist on the webs and see if it matches any of the various forms. I'm in no way an expert, so please don't take my word for it :rolleyes:

  • I found this Informative 1
Link to post
Share on other sites

I think you’re both right. I found a detail shot of a mica schist and it has the same wavy/ridged surface pattern. And it definitely flakes like mica. 

Thank you so much!

Link to post
Share on other sites

There is a lot of pyrite in the mountains around Denver but it would be almost unheard of to find a 10 cm piece lying on the ground unless it was just mined and dropped- besides that, exposed pyrite rusts.


one additional clue to sort the two- pyrite is very dense- it will feel heavy for it's size

it is twice the density of mica



Link to post
Share on other sites

The weight feels as I would expect it to, not too heavy. So I believe it’s likely mica. I didn’t know that about pyrite... that it rusted or that it’s more dense. Thanks for the insights!

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Create New...