Unique wood from Round Mountain Silt, anyone seen anything like this?

[H. Drax]

Been going through an old collection I haven't looked at in many years and in it are 15 or 20 pieces of wood, collected at the Ernst quarry back in the 90s. I haven't seen any similar examples from Sharktooth Hill or elsewhere.

 

The pieces are somewhat fragile and often partially hollow with small (druzy?) purplish crystals on the interior. The rest is mostly composed of the same purplish-black material but man also show a tougher translucent outer crust. Some of the interiors of these pieces also contain powdery, lightweight chunks of brown matter. 

 

Based on appearance and the local geology as well as the preservation of flora from another miocene site in the region (see Reynolds p.114) I'm guessing the dark purplish stuff is pyrolusite or a similar manganese mineral. I assume the tougher clear stuff is microcrystalline quartz. The powdery brown stuff I cannot explain except as mummified wood, but I haven't found any pre-pliocene examples in the fossil record. I'm not a wood guy in general though so maybe there's more out there. What do you think? Something of research value?

 

 

 

 

A small piece (~2.5 cm square) with the two primary minerals.

 

 

Typical piece. Largest is about 15 cm. 

 

 

The mysterious Brown Matter. Very hard to get a good photo since it's mostly deep in the "geode."