Context: Naturally occurring glass, especially the volcanic glass obsidian, has been used by many Stone Age societies across the globe for the production of sharp cutting tools and, due to its limited source areas, was extensively traded. But in general, archaeological evidence suggests that the first true glass was made in coastal north Syria, Mesopotamia or ancient Egypt. The earliest known glass objects, of the mid third millennium BCE, were beads, perhaps initially created as accidental by-products of metal-working (slags) or during the production of faience, a pre-glass vitreous material made by a process similar to glazing.

Question: What kind of glass exists in nature?
Answer: obsidian

Question: Obsidian is what type of glass?
Answer: volcanic

Question: What was obsidian used to make in prehistoric times?
Answer: cutting tools

Question: When are the oldest beads thought to have been made?
Answer: mid third millennium BCE

Question: What glass-like material is made with a method related to glazing?
Answer: faience

Question: What kind of glass exists in Egypt?
Answer: Unanswerable

Question: Obsidian is what type of slag?
Answer: Unanswerable

Question: What was obsidian used to make in falence processes?
Answer: Unanswerable

Question: What glass-like material is made with a method related to sharp cutting?
Answer: Unanswerable

Question: What suggests that the first true glass was accidental?
Answer: Unanswerable