Easton's Bible Dictionary
Hebrews pitdah (Ezek. 28:13; Revelation 21:20), a golden yellow or "green" stone brought from Cush or Ethiopia (Job 28:19). It was the second stone in the first row in the breastplate of the high priest, and had the name of Simeon inscribed on it (Exodus 28:17). It is probably the chrysolite of the moderns.
Noah Webster's New International Dictionary of the English Language
1. (n.) A mineral occurring in rhombic prisms, generally yellowish and pellucid, also colorless, and of greenish, bluish, or brownish shades. It sometimes occurs massive and opaque. It is a fluosilicate of alumina, and is used as a gem.
2. (n.) Either one of two species of large, brilliantly colored humming birds of the Topaza, of South America and the West Indies.