This stone dictionary will give you insight into the world of minerals, generally describing most of our utilized materials.

Stones by first letter: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Stones “O” Shown Below


Obsidian – A naturally occurring volcanic glass. Because glass becomes fine grained mineral crystals with time, no Obsidian has been found that is older than the Cretaceous period. Not all Obsidian is black, or even dark, some are actually nearly colorless. Obsidian has a rich history over time, including being polished to create early mirrors and being popular in making arrowheads due to its fracturing tendencies making it easier to sculpt than many other materials.



Ocean Jasper – Jasper is a form of chalcedony. Ocean Jasper, or Orbicular Jasper, is a variety that exhibits colorful orbs and spheres along with waves of color, often green, white, peach, orange, yellow and pink hues. This rare form of Jasper is found only in one area of Madagascar, and receives its name due to its location along the coastline which can only be reached by boat and mined during low tide.



Olivine – The mineral Olivine is a transparent green hued stone. The gem quality version is known as Peridot, though it is named for its typical olive green coloration. Olivine is found in many locations throughout the world; one of the most interesting occurrences is the Olivine discovered in Meteorites, Comets and Asteroids.

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Onyx – Onyx is a chalcedony. In ancient Greece, all tones of chalcedony were known as Onyx. The Romans are responsible for narrowing the name to refer only to the black and dark brown hues of chalcedony. Today, many people still only associate the name with a solid, deep black hue, though this coloration is actually the least common occurrence of chalcedony.



Opal – Opal is a hydrated amorphous form of silica. The water content of an opal can be up to 20% of its weight and many opals display more fire after being soaked in water. A mineraloid, rather than a minerals, this stone is the National Gemstone of Australia, where a vast percentage of all opals are found. Opals can be transparent or opaque and occur in many varieties and colors.

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Stones by first letter: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z