Miocene Petrified Plant?

[DPS Ammonite]

This piece of chert is about 10 millions years old that was found east of San Francisco, CA in volcanic and lakebed deposits. What are the 0.3 to 0.6mm wide tubes- palm fiber?

[ynot]

Does not look like the palm wood I have seen. The fibers in the palm wood are straighter and more uniformly distributed.

Can You post pictures of the whole piece?

Maybe a root structure(?).

[DPS Ammonite]

Here are other views of the 8cm long chert piece.

[ynot]

Yeah, that looks more palm like. Guess I am not used to seeing it in magnification.

Nice piece.

Tony

 

PS That should be called agate.

[DPS Ammonite]

Thanks Tony. The geologist side of me calls it chert, the lapidarist side of me calls it agate- same similiar thing.

[ynot]

Agate /ˈæɡət/ is a cryptocrystalline variety of silica, chiefly chalcedony, characterised by its fineness of grain and brightness of color. Although agates may be found in various kinds of rock, they are classically associated with volcanic rocks and can be common in certain metamorphic rocks.[1]

 

Chert (pronunciation: /ˈtʃɜːrt/) is a fine-grained silica-rich microcrystalline or cryptocrystalline sedimentary rock that may contain small fossils. It varies greatly in color (from white to black), but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements present in the rock, and both red and green are most often related to traces of iron (in its oxidized and reduced forms respectively).

 

I think they are different forms of quartzite.