What Is Crystalline Silica (Quartz)?

"Silica" is a term that broadly refers to the mineral compound silicon dioxide (SiO2). Silica can be crystalline or amorphous.

The difference between a crystalline solid and an amorphous solid is that an amorphous solid does not have a particular melting point. Amorphous solids melt over a wide range of temperatures. By comparison, a crystalline solid has a specific melting point at which the solid becomes a liquid. At the molecular level, there is a significant structural difference between the two. Crystalline structures are sharper. Amorphous structures are smoother.

This structural difference contributes to the fact that crystalline silica is significantly more hazardous to employees than is amorphous silica. In addition to causing the disabling and irreversible lung disease known as silicosis, crystalline silica has been classified as a human carcinogen by the International Agency for Research on Cancer. As it is typically used in this document, the term "silica" refers specifically to crystalline silica. The term "crystalline silica" and "quartz" refer to the same thing. Crystalline silica is a natural constituent of the earth's crust, and is a basic component of sand and granite. Crystalline silica is an important industrial material, and occupational exposure occurs across a broad range of industries, including construction, mining, manufacturing, maritime, and agriculture.

Many of the most beautiful beaches in the world are made of crystalline silica. But no need to cancel your vacation! Except for a possible sunburn, no harm will come to you from walking on the beach. As we will learn later in this course, the danger comes when silica is inhaled.

To learn more about Silica Safety visit our General & Maritime Silica Safety Online Training web page.