Properties of Glass

Chapter 1: Properties of Glass

Glass is one of the most widely used materials in today s world. It is a material that is transparent, brittle, and hard. From the mirror in the morning to the milk glass on the breakfast table, from the windshields of vehicles to the telescopic lenses used by scientists, and from its use in laser communication to its use as art and ornamental material, glass has found application in almost every sphere of life. Glass can be manufactured using low-cost raw materials and techniques.

This handbook explains some basic concepts of glass. It describes the types, chemical properties, and the process of formation of glass. It also lists some physical, mechanical, thermal, and optical properties of some commonly used types of glass.

Types of Glass

Most glass contains silica as the chief ingredient. The rate of cooling, proportion of raw materials, and process of formation are varied to achieve the desired properties in glass.

Natural Glass

Based on the mode of formation, natural glass is classified into different types, such as obsidian, tektites, Libyan Desert, and fulgurites.


Obsidian is a hard glass that is formed inside a volcano when silica masses fuse because of high temperature. The splinters of this glass are transparent and translucent. However, because of the high concentration of impurities, the glass is opaque and often black in color with a shiny appearance. Obsidian was discovered by the Egyptians and Iranians in ancient times and has been used in tools, weapons, and ornaments ever since.