Chalcedony – Agate

Appearance:

• semitransparent to opaque 
• virtually all colors

Variety and Trade Names:

• agate – chalcedony with curved or angular bands or layers
• moss agate or mocha stone – chalcedony with green, black, or brown inclusions that look like moss
• onyx – chalcedony composed of straight, parallel layers of different colors
• sardonyx – onyx showing bands of sard colors alternating with either white or black parallel bands
• carnelian onyx – onyx showing bands of carnelian colors alternating with either white or black parallel bands
• dendritic agate – chalcedony with dark inclusions resembling tree branches

Stone Information from:

Gem Reference Guide, by GIA, ISBN 0-87311-019-6
Gemstones of the world, Third Edition, by Walter Schumann, ISBN 1-4027-4016-6
https://www.mindat.org/min-51.html
https://www.gemdat.org/gem-51.html