Mahogany black lace obsidian from Oregon is a double flow obsidian with shades of brownish red with black and clear to smoky areas which make beautiful lace patterns. (Stock 542) Rough sizes are from 1-15 pounds, plus. Obsidian is great for jewelry or handknapped knife blades, spear points and more. See a sample cabochon of mahogany black lace obsidian. The price listed is for one pound of rough.