Question for you geologists/rockhounds...?

Question

I am in the process of making a Japanese style garden but I would like to know what type of rock a person could get that is black and quite large. Much like the ones shown in this picture: http://phototravels.net/japan/pcd3860/rock-garden-tofukuji-1.html

I am looking for the name of a rock that resembles the ones shown. (ie. basalt).

Answer 1

Well its hard to determine what the rocks in the photo are, I can't see enough detail. However, it stands to reason they may be scoria, its vesicular and can be very dark even black.

A good landscapping company that sells rock should have scoria available in the large boulder size. Because scoria is vesicular, its lightweight and easy to move about. A big block of basalt will weigh a lot! Plus if a 2 foot tall oblong boulder of basalt were to fall over onto a kid or pet, well oopsies!

Answer 2

Yes, basalt is a good choice.  You may want to see if you can find some dark obsidian, also

Answer 3

black marble, gabbro (my favorite coming from gore mountain, New York), but basalt would by far be the cheapest, and the most likely rock in the photo.

Answer 4

You answered your own question!!