RE:RE:RE:New Rock exposureThe silver-lead-zinc veins in the Hercules rhyolite are "veins" meaning mineralized fractures. They tend to be thin and tabular and linear in cross section. I'm not seeing any veining in the photo. That looks like mineralized volcanic rock to me. The Silver is native/metal Silver. In a freshly broken rock it would shine like aluminum. I'm not seeing that either. All of this said you can only tell so much from a grainy photo.
I suspect that they released the photo for a reason - "look what we found!"