Nevada tree trunk/plant?

[Terry H]

Trying to find out what this is. Found in the Northern Nevada desert. It looks like a round tree trunk 10 inches across. Half of the outer surface is somewhat smooth and the other half has a stepped pattern that reminds me of how some plants grow stems upwards. The pic that shows this section maybe upside down. The photographer and I aren't sure whats up or down. The texture is like glass, we think its opalized? Very sharp edges and smooth. It's brittle. The color is brown on outside with white calcium patches. Inner area is a solid carmel color with tint of green, there are no flashes of rainbow colors or clear crystals. There are no other patterns, dots, striations, or wood like grain. It was found among volcanic and igneous rock field. Searched for more similar but none found on surface. 

[Rockwood]

Fluid vent is my first thought. Think super-saturated mineral water in a drying spring hole.

[Terry H]

Well, that explains why I couldn't find any kind of plant similar to this. I now have a different path to explore. Interesting. Thanks for your comment.