Black Indigo Rock Gravel Northern California quarry, this material ships in bulk to all major regions of Central and Northern California. Shipped in SuperEarth-sacks throughout California and where requested. A fine grained black basalt rock, with a smattering of brown or tan coloring that is the darkest black rock, other than lava cinders available. This is the most true black rock sold in California, perhaps in the whole Southwest. Designers should be able to use this unique material to produce some great works. This bold black hard rock gravel material is sold as boulders, rip rap, gravel and crushed stone fines.