Glass in figures

1,710°C is the melting point of crystalline quartz, which consists of SiO2 (silicon dioxide), the main component of quartz sand. If this chemical compound is melted, the SiO2 molecules arrange themselves in a very specific pattern: the oxygen atoms form tetrahedra – pyramids with four triangular faces – and the silicon atoms can be found in the middle of each tetrahedron. In a quartz crystal, this tetrahedral structure continues periodically without any deviation. If the tetrahedra do not form a continuously periodic structure and if further components are added to the melt, a silicate glass is produced. This can be formed at temperatures of 500 to 800°C.

4,000 years People have been making glass for thousands of years. The Egyptians first made hollow glass around 1500 BC. It was used as a container for ointments and oils. The oldest known glass vessel can be dated back to around 1450 BC. It is a chalice bearing the name of Egyptian Pharaoh Thutmose III.

650 BC the first written formula for glass was recorded on papyrus and kept in the library of Ashurbanipal, King of Assyria. It said: »Take 60 parts of sand, 180 parts of seaweed ash and 5 parts of chalk – and you get glass«.

1,000,000 years can pass before glass dissolves. The reason: glass can be absolutely chemically inert. This means that a glass vessel does not react with its surroundings or its contents. This is a great advantage for the shelf life of food and medicines. It also means that the material can be recycled almost indefinitely by being repeatedly shaped into new bottles, glasses or building materials. Due to its chemical stability, glass is considered one of the most important options for the permanent containment of radioactive elements.

30,000,000 years ago, a meteorite hit the desert of North Africa and melted the desert sand in the region, resulting in millimetre to decimetre-sized pieces of quartz glass in different shades of colour. Jewellery was made from this »Libyan desert glass« in ancient Egypt. For example, a scarab made of this glass adorns the breastplate that was discovered in the tomb of Pharaoh Tutankhamun exactly 100 years ago.

39,000 km is the length of the longest optical fibre in the world’s longest submarine cable, »Sea-Me-We 3«. It spans the internet network between Germany, Japan, and Australia.

1665 is the year Louis XIV, King of France, granted financier Nicolas Dunoyer and his partners the exclusive right to manufacture mirror glass. The royal mirror glass manufactory developed the revolutionary table rolling process and the world’s first industrial glass company was established in the small village of Saint-Gobain in Normandy. Saint-Gobain mirrors have adorned the gallery in the Palace of Versailles near Paris since 1684.

1847 is the year when glass Christmas tree decorations were »born out of necessity« in Lauscha, Thuringia. The story goes that a glassblower and his family had become so impoverished that they couldn’t afford to decorate their Christmas tree with the usual fruits, nuts and sweets. So instead, he formed fruits and nuts out of hollow glass – the forerunners of today’s Christmas baubles. The department store founder Frank Winfield Woolworth made the Christmas tree decorations from Lauscha an export hit around 1880, and they have since been sold all over the world.

1875 is the year Otto Schott obtained his doctorate from the University of Jena, where he gave his name to the Otto Schott Institute of Glass Chemistry in 1967 (now the »Otto Schott Institute of Materials Research«). Otto Schott is considered the founding father of systematic glass chemistry research.