Stone Age humans were the first people to discover glass in the form of natural glass, such as obsidian or fulgurites. They used these materials for tools and decorations. Man-made glass wasn't invented until 3500 B.C. by ancient Mesopotamians, Egyptians or Syrians.
Obsidian is natural glass created by the high pressure and heat of volcanoes, while fulgerites are glass formations made from sand superheated by lightning. An ornamental scarab found with Tutankhamun's body was crafted from clear fulgerite glass, likely from the Libyan Desert, that is over 26 million years old. Glass was first used by humans as beads and glazed coatings for pottery, and the Phoenicians transported these goods around the Mediterranean Sea. Hollow glass constructions first appeared in Mesopotamia in the 16th century B.C.