The southern edge of the Piedmont Pines neighborhood butts against Joaquin Miller Park, and there’s no reason to visit if you don’t happen to live there—except if you like serpentinite. The street named Las Aromas dips into the belt of serpentinite that extends up and over the ridge to Serpentine Prairie, and the rock type is well exposed. One resident has done a lot of landscaping in this inhospitable rock type.
The scaly structure is typical of serpentinite, and here it’s fairly close to the Hayward fault. Farther uphill is this exposure, where the grain of the rock is parallel to the street.
Its blue-green color is striking. And there are a few spots where friction in the recent geologic past has turned it glossy. The rocks aren’t as spectacular as Serpentine Prairie itself, but they’re still noteworthy.
I never tire of our state rock. Speaking of Serpentine Prairie, today on KQED Science there’s a story on the ongoing effort to propagate the rare Presidio Clarkia. (I photographed it a few years ago before they fenced off the area.)
Oakland Geology 
15 December 2014 at 10:43 am
Some nice outcrops there, any opal or magnesite veins in it? Looks pretty solid and has nice textures. Thanks for sharing!
16 December 2014 at 9:39 pm
Sorry, it was only a reconnaissance visit. I do want to come back, though.