https://imagizer.imageshack.us/v2/520x1069q90/834/jykbl.jpg
All three rocks are from Black Sand Beach at the Marin Headlands just north of San Francisco's Golden Gate Bridge.
The middle rock is the area's predominant radiolarian chert.
The top rock has the white intrusions into the chert (the black perhaps is the remains of a black smoker, because IIRC--not sure since I haven't hiked down there lately--there were formations such as this http://www.marin.edu/~jim/ring/images/mang.gif nearby).
The bottom rock is mostly the white rock.
*** Are the white intrusions in the photo above marble? ***
Here's another photo from the beach http://www.nps.gov/goga/forteachers/images/Limestone-outcrop.jpg
While googling I found a cool photo of nearby "folded ribbon chert" at http://www.nps.gov/goga/forteachers/chert-faq.htm
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