Orbicular jasper is a variety of jasper

Jasper

Jasper, a form of chalcedony, is an opaque, impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. This mineral breaks with a smooth surface, and is used for ornamentation or as a gemstone. It can be highly polished and is used for vases, seals, and at one time for...

 which contains variably-colored orbs or spherical inclusions or zones. In highly silicified rhyolite

Rhyolite

This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade.Rhyolite is an igneous, volcanic rock, of felsic composition . It may have any texture from glassy to aphanitic to porphyritic...

 or tuff

Tuff

Tuff is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff is sometimes called tufa, particularly when used as construction material, although tufa also refers to a quite different rock. Rock that contains greater than 50% tuff is considered...

, quartz

Quartz

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

 and feldspar

Feldspar

Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....

 crystallize in radial aggregates of needle-like crystals which provide the basis or seed for the orbicular structure seen in this kind of jasper. The material is quite attractive when polished and is used as an ornamental stone or gemstone

Gemstone

A gemstone or gem is a piece of mineral, which, in cut and polished form, is used to make jewelry or other adornments...

.

Various local or commercial names have been used for the material, such as kinradite, oregonite, owyhee jasper, ocean jasper and poppy-patterned jasper, depending on the source. Poppy-patterned jasper or poppy jasper is the varietal name for material from Morgan Hill

Morgan Hill, California

Morgan Hill is a city located in the southern part of Santa Clara County, California, United States. Founded on November 10, 1906, the city was named after Hiram Morgan Hill, a San Franciscan who built a country retreat home there in 1884...

, Santa Clara County, California

Santa Clara County, California

Santa Clara County is a county located at the southern end of the San Francisco Bay Area in the U.S. state of California. As of 2010 it had a population of 1,781,642. The county seat is San Jose. The highly urbanized Santa Clara Valley within Santa Clara County is also known as Silicon Valley...

. The trade name ocean jasper is used for a variety found along the intertidal shores of northeast Madagascar

Madagascar

The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

. In Nebraska

Nebraska

Nebraska is a state on the Great Plains of the Midwestern United States. The state's capital is Lincoln and its largest city is Omaha, on the Missouri River....

 orbicular jasper is found in altered rhyolite beds noted for a variety of jaspers and related agate

Agate

Agate is a microcrystalline variety of silica, chiefly chalcedony, characterised by its fineness of grain and brightness of color. Although agates may be found in various kinds of rock, they are classically associated with volcanic rocks and can be common in certain metamorphic rocks.-Etymology...

s.