I have a Harbor freight tools brick saw that I have used for over 12 yrs. Replace the blade with a dry cut turbo diamond blade and mist with water while you cut keeps the dust down and keeps heat down that can crack fragile rock. This advise is for soft materials, and or "some" heat treated stone.
Cuts obsidian close to the same rate as a table saw with a hardwood, and you get thick slabs for knife blades.