from The Century Dictionary.
- noun In petrography, metamorphosed rock composed largely of minute granules of green hydrous ferrous silicate.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun mineralogy A
hydrated ferrous silicaterelated to serpentine
Sorry, no etymologies found.
The original condition is indicated by the facts that deep below the surface, in zones protected from weathering solutions, siderite and greenalite are abundant, and that they show complete gradation to hematite in approaching the surface.
When originally deposited the iron was partly hematite (perhaps some magnetite) and largely in the form of iron carbonate (siderite) and iron silicate (greenalite), interbanded with chert.