There are quite a few breccias occuring in the East Range. There have so far been four types recognized. The most common, by far, is a breccia characterized by white quartz containing angular fragments of dark blue or black chert or black diabase / andesite. The host rock for this is considered to be the Valmy Quartzite member or the Valmy Argillite or Chert member. Many of these are in the Valmy first and second member.
This outcrop strikes North / South and you are looking West. What you don't see on the West side of this outcrop is that it appears to dip about 30 degrees to the West. This suggests that the breccia may have been stratabound by the Valmy second member. Further West, about 50 meters, are two more narrow, breccia outcroping veins striking West.
This is a substancial breccia near the Thacker Camp. The areal extent approaches 1/2 an acre.
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The second type of Breccia, and again common, are breccia or quartz pipes of relatively small size near intrusives. There are three small pipes on Rawhide Pass.
This pipe is about 2 meters across and sits on top of the pass. The pick photo below shows a curiously banded chert that appears to wrap around the pipe.
A piece of banded chert sits atop Valmy argillite member.
These three pipes seem to be genitically related. They appear to line up on an East-West fracture.
The third type is relatively rare. It is a calc-silicate breccia formed in the marble near intrusives.
This unusual breccia was a float. The author has found a very dark version of this float as a layer on the periphery of the marble in a marble shelf near a hornblend diorite intrusive.
This breccia has be only found as float in upper Willow Creek so far.
Jim Dixon of Tucson says that the groundmass has a limestone fabric to it. Cavities are as large as two inches. This rock weighs about 100 pounds. Sone cavities contain hot spring sinter (boytroidal quartz).
An example of hit spring sinter. This was collected as float in upper Willow Creek.