It flakes very nicely into really sharp points.

问题描述:

It flakes very nicely into really sharp points.
obsidian is a black,
volcanic,well,almost like glass.It flakes very nicely
into really sharp points.The sharpest tools of the entire Stone Age
were made of obsidian.这个是原文的语境

黑曜石是黑色的,火山喷发形成的,well?的玻璃.有规则的逐层剥落形成锋利的尖端.石器时代最锋利的工具就是用黑曜石制作的.