An amorphous substance, usually transparent or translucent. Glass is formed by a fusion of silicates (sometimes oxides of boron or phosphorus) with a flux and a stabilizer into a mass that cools to a rigid condition without crystallization.
Glass was known in the ancient world from about 2600 B.C. in Egypt. In Egypt and Phoenicia glass was opaque and was used chiefly to make ornamental objects—especially beads, jewelry, and small bottles. The value of glass in ancient times may be indicated in Job where the value of glass is equated with that of gold and is used in parallel with jewels (Job 28:17). The Egyptians and Phoenicians made small bottles for perfume by welding sticks of glass round a core of sand and clay built around a bar of metal. The core and bar were removed after the glass cooled.
Transparent glass was not made until New Testament times as a luxury item. During this period, Alexandria, Egypt, became world famous as a center for the production of glassware. Such items as beakers, bowls, flasks, goblets, and bottles were made from the transparent glass. Corinth became known for the production of glass after the time of Paul.
John probably had the transparent variety of glass in mind when he wrote Revelation. He described the walls and streets of the new Jerusalem being made of pure gold. The gold of the walls and streets was so pure, it was as clear as glass (Revelation 21:18,Revelation 21:21).
John also described the sea as being like glass (Revelation 4:6;
Revelation 15:2). Here the reference is probably not so much to transparency as to calmness. It has often been stated that the Israelites had a fear of the sea which always seemed to be in a state of chaos and tumult. The sea that John saw around the throne of God was not in a constant uproar; this sea was as smooth as glass.
The KJV uses glass in five other passages where a polished metal mirror is probably being referred to (Job 37:18;
1 Corinthians 13:12;
2 Corinthians 3:18;
James 1:23). Glass was not used to make mirrors in biblical times.