Search results
Results from the WOW.Com Content Network
Labradorite ((Ca, Na)(Al, Si) 4 O 8) is a calcium-enriched feldspar mineral first identified in Labrador, Canada, which can display an iridescent effect . Labradorite is an intermediate to calcic member of the plagioclase series. It has an anorthite percentage (%An) of between 50 and 70. The specific gravity ranges from 2.68 to 2.72.
Nuummite is usually black in colour and opaque. It consists of two amphiboles, gedrite and anthophyllite, which form exsolution lamellae that give the rock its typical iridescence. Other common minerals in the rock are pyrite, pyrrhotite and chalcopyrite, which form shimmering yellow bands in polished specimens.
In some stones, the inclusion of small, white, radially clustered crystals (spherulites) of the mineral cristobalite in the black glass produce a blotchy or snowflake pattern (snowflake obsidian). Obsidian may contain patterns of gas bubbles remaining from the lava flow, aligned along layers created as the molten rock was flowing before being ...
A single iridescent species of gecko, Cnemaspis kolhapurensis, was identified in India in 2009. [22] The tapetum lucidum , present in the eyes of many vertebrates, is also iridescent. [ 23 ] Iridescence is known to be present among prehistoric non-avian and avian dinosaurs such as dromaeosaurids , enantiornithes , and lithornithids . [ 24 ]
An iridescent ammonite from Madagascar Map of North America highlighting the shallow inland sea present during the mid-Cretaceous period. Ammolite comes from the fossil shells of the Upper Cretaceous disk-shaped ammonites Placenticeras meeki and Placenticeras intercalare , and (to a lesser degree) the cylindrical baculite , Baculites compressus .
Unusual specimen of goethite replacing a gypsum stalactite; the center is hollow.From Santa Eulalia, Chihuahua, Mexico.. Goethite (/ ˈ ɡ ɜːr t aɪ t /, [6] [7] US also / ˈ ɡ oʊ θ aɪ t / [8] [9]) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the α-polymorph.
The black opal is said to be some of the best examples found in Australia. Andamooka in South Australia is also a major producer of matrix opal, crystal opal, and black opal. Another Australian town, Lightning Ridge in New South Wales , is the main source of black opal, opal containing a predominantly dark background (dark gray to blue-black ...
Scoria or cinder is a pyroclastic, highly vesicular, dark-colored volcanic rock formed by ejection from a volcano as a molten blob and cooled in the air to form discrete grains called clasts. [1] [2] It is typically dark in color (brown, black or purplish-red), and basaltic or andesitic in composition.