Orthoclase
Opal is a valuable mineral that starts with the letter "O." It is known for its unique play of colors and is often used in jewelry.
Opal is a mineral.
Opal and onyx are two I can think of spontaneously.
ore
Osmium is a mineral. It is a chemical element and has the symbol Os.
Overcoat, Orange hat, Old trousers. an Opal ring ,or necklace, etc..
Olivia, Olympia, Omega, Olive, Opal, Ophira, Oprah, Orinda Hope I helped! -Starrynight98
oh order of okay ordinary orb optional on oval over ogre orange old or opal ongoing
· Onyx · Opal
Oldsmobile, Opal
octopus, optomotrist, opal, oscar, orange,
Opal fruits. A British candy, google it.