🔎 UNIDENTIFIED Lake Berryessa mystery rock

[Honcho707]

Found this guy at lake Berryessa in California while looking for Jasper and petrified wood. At first glance it was black with specs of gold in it was non magnetic. When I looked at it under a rock microscope 🔬 I was surprised to see that the structure was crystal like. I have not been able to identify this rock for life of me. Hopefully someone knows this guy from experience

 

[Clay Diggins]

It's Serpentine. A very common rock in the Lake Berryessa region particularly to the west and north of the lake.