IC 6493 Opals
- Organization:
- The National Institute for Occupational Safety and Health (NIOSH)
- Pages:
- 12
- File Size:
- 636 KB
- Publication Date:
- Sep 1, 1931
Abstract
The opal , long in disfavor because it was considered " unlucky, " has
become much more popular in recent years . For variety and beauty of color
the precious opal is without a peer . These colors do not come from any
chemical constituent but are produced by structural peculiarities , which in
varying degrees deflect the light rays entering the stone and give a prismatic
play of hues .
Citation
APA: (1931) IC 6493 Opals
MLA: IC 6493 Opals. The National Institute for Occupational Safety and Health (NIOSH), 1931.