A silvery-grey ore of arsenic, a mixed arsenide and sulfide of iron, FeAsS.
Any of several fibrous mineral forms of magnesium silicate, used for fireproofing, electrical insulation, building materials, brake linings, and chemical filters; The small fibres can cause cancer when lodged in the lungs.
A semipellucid, uncrystallized variety of quartz, presenting various tints in the same specimen. Its colors are delicately arranged in stripes or bands, or blended in clouds.
A form of chrysoberyl that displays a colour change dependent upon light, along with strong pleochroism.
A transparent purple variety of quartz, used as a gemstone.
The bluish-green colour of the sea.
A variety of translucent quartz, spangled throughout with scales of yellow mica.
A blue vitreous mineral; a basic copper carbonate, with the chemical formula Cu2+3(CO3)2(OH)2.
A hard rock of varied mineral content; volcanic in origin, it makes up much of the Earth's crust.
(mineralogy) A mineral of pegmatite deposits, often used as a gemstone.
a very widely distributed crystalline form of calcium carbonate, CaCO3, found as limestone, chalk and marble
A unit of weight for precious stones and pearls, equivalent to 200 milligrams.
A form of fine-grained quartz that is nearly transparent or has a milky translucence; it fractures conchoidally.
a greenish-yellow colour, like that of a lemon.
A solid (mineral quartz or otherwise) composed of an array of atoms possessing long-range order and arranged in a pattern which is periodic in three dimensions.
A glimmering glass-like mineral that is an allotrope of carbon in which each atom is surrounded by four others in the form of a tetrahedron.
A saline evaporite consisting of a mixed calcium and magnesium carbonate, with the chemical formula CaMg(CO3)2;
Of a rich green colour.
Any one of the flat surfaces cut into a gem.
Any of a large group of rock-forming minerals that, together, make up about 60% of the earth's outer crust.
Any transparent to translucent opal with a warm body colour of yellow, orange, or red.
A widely occuring mineral (calcium fluoride), of various colours, used as a flux in steelmaking, and in the manufacture of glass, enamels and hydrofluoric acid.
Hard transparent minerals that are often used as gemstones and abrasives.
a gem, usually made of minerals.
A nodule of stone having a cavity lined with mineral or crystal matter on the inside wall
The science that studies the structure of the earth (or other planets), together with its origin and development, especially by examination of its rocks
A common and widely-distributed metamorphic rock having bands or veins.
A group of igneous and plutonic rocks composed primarily of feldspar and quartz. Usually contains one or more dark minerals, which may be mica, pyroxene, or amphibole. Common colors are gray, white, pink, and yellow-brown.
A mineral consisting of the hydrated calcium sulphate. When calcined, it forms plaster of Paris.
An iron ore, mainly peroxide of iron, Fe2O3.
one of the major groups of rock that makes up the crust of the Earth; formed by the cooling of molten rock, either below the surface (intrusive) or on the surface (extrusive)
An addition or annex to a group, set, or total.
A semiprecious stone either nephrite or jadeite, generally green or white in color, often used for carving figurines.
A pyroxene mineral, a sodium aluminium silicate with the chemical formula Na(Al,Fe3+)Si2O6, found in metamorphic rocks.
Any bright-coloured kind of chalcedony apart from cornelian.
A unit of fineness or concentration equalling 1/24 parts gold in an alloy.
A plagioclase feldspar, the fourth member of the Albite-Anorthite solid solution series.
A person who cuts, polishes, engraves, or deals in gems.
A deep blue stone, used in making jewelry.
An abundant rock of marine and fresh-water sediments; primarily composed of calcite (CaCO₃); it occurs in a variety of forms, both crystalline and amorphous.
any sediment, dominated by silt, of eolian (wind-blown) origin
Shine, polish or sparkle.
The molten matter within the earth, the source of the material of lava flows, dikes of eruptive rocks, etc.
It has also been called lodestone.
A bright green mineral, a basic copper carbonate, Cu2CO3(OH)2; one of the principal ores of copper.
one of the major groups of rock that makes up the crust of the Earth; consists of pre-existing rock mass in which new minerals or textures are formed at higher temperatures and greater pressures than those present on the Earth's surface
A relatively small (sand- to boulder-sized) fragment of debris in a solar system that produces a meteor when it hits the atmosphere
The name of a group of hydrous aluminosilicate minerals characterized by highly perfect cleavage, so that they readily separate into very thin leaves, more or less elastic.
Any naturally occurring inorganic material that has a (more or less) definite chemical composition and characteristic physical properties.
A translucent gemstone, an orthoclase feldspar, that has a pearly lustre.
A semi-precious stone, one of the two types of stone commonly referred to as jade, (the other being jadeite).
a type of black glass produced by volcanos
A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity, of the chemical formula SiO2·nH2O.
Potassium aluminum silicate, KAlSi3O8, a common feldspar of igneous, plutonic, and metamorphic rocks.
A transparent olive-green form of olivine, used as a gem.
A light, porous type of pyroclastic igneous rock, formed during explosive volcanic eruptions when liquid lava is ejected into the air as a froth containing masses of gas bubbles. As the lava solidifies, the bubbles are frozen into the rock.
The common mineral iron disulfide (FeS2), of a pale brass-yellow color and brilliant metallic luster, crystallizing in the isometric system.
A flow of volcanic ash, dust, rocks and debris that cascades down the slope of a volcano during an eruption.
The most abundant mineral on the earth's surface, of chemical composition silicon dioxide, SiO2. It occurs in a variety of forms, both crystalline and amorphous. Found in every environment.
A reddish colored type of quartz
A clear, deep, red variety of corundum, valued as a precious stone.
A sedimentary rock produced by the consolidation and compaction of sand, cemented with clay etc.
a clear deep blue variety of corundum, valued as a precious stone.
A variety of carnelian, of a rich reddish yellow or brownish red color.
a variety of onyx or chalcedony.
Any crystalline rock having a foliated structure and hence admitting of ready division into slabs or slates.
one of the major groups of rock that makes up the crust of the Earth; formed by the deposition of either the weathered remains of other rocks, the results of biological activity, or precipitation from solution
An instrument that automatically detects and records the intensity, direction and duration of earthquakes and similar events.
Sort of or somewhat precious or valuable.
Sinuous; curving in alternate directions.
Mud or fine earth deposited from running or standing water.
a soft rock, rich in talc, also containing serpentine and either magnetite, dolomite or calcite
A mineral of alkaline igneous and plutonic rocks that are low in silica, of the chemical composition of sodium aluminum silicate with chlorine, Na4Al3Si3O12Cl.
any of several hard minerals of cubic symmetry that are mixed oxides of magnesium and aluminium and are used as gemstones of various colours
A mineral deposit of calcium carbonate, in shapes similar to icicles, that hangs from the roof of a cave.
A mineral deposit of calcium carbonate, in shapes similar to icicles, that lie on the ground of a cave.
A soft mineral of a soapy feel and a greenish, whitish, or grayish color, usually occurring in foliated masses.
(anatomy) The bone of the ankle.
a clear, yellowish-brown gemstone.
A complex black or dark coloured borosilicate mineral.
Of, or resembling glass; glassy
A hard rubber made by vulcanization with sulfur; ebonite
any piece of rock having a different origin to that of the igneous rock in which it is found
A mineral occurring in tetragonal crystals, usually of a brown or grey colour and consisting of silica and zirconia.
A mineral with orthorhombic crystals, Ca2Al3(SiO4)(Si2O7)O(OH).