Encyclopedia - Onyx: Encyclopedia - Onyx
Onyx is a banded variety of chalcedony, a cryptocrystalline form of quartz. The colors of its bands are white and black. Sardonyx is a va...   » Read the article

Encyclopedia - List Of Minerals: Encyclopedia Ii - List Of Minerals - Z
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 Top of page — See also — External links ... See also:List of minerals, List of...   » Read the article

Encyclopedia - Industrial Minerals: Encyclopedia Ii - Industrial Minerals - Examples And Applications
Typical examples of industrial rocks and minerals are limestone, clays, sand, gravel, diatomite, kaolin, bentonite, silica, barite, gypsu...   » Read the article

Encyclopedia - Celestite: Encyclopedia - Celestite
Celestite (SrSO4) is a mineral consisting of strontium sulfate. The mineral is also known as celestine and is named for its occasional de...   » Read the article

Encyclopedia - Anorthite: Encyclopedia - Anorthite
Anorthite is one of the plagioclase feldspars, an important group of minerals abundant in the Earth's crust. Anorthite's chemical formula...   » Read the article

Encyclopedia - Chalcedony: Encyclopedia - Chalcedony
Chalcedony is one of the cryptocrystalline varieties of the mineral quartz, having a waxy luster. Chalcedony may be semitransparent or tr...   » Read the article

Encyclopedia - Variscite: Encyclopedia - Variscite
Variscite AlPO4·2H2O, hydrated aluminium phosphate, is a relatively rare phosphate mineral. It is sometimes confused with turquoise, how...   » Read the article

Encyclopedia - Stibnite: Encyclopedia - Stibnite
Stibnite, sometimes also called antimonite, is a sulfide mineral. It crystallizes in the orthorhombic system, has hardness 2 and a grey c...   » Read the article

Encyclopedia - Chrysocolla: Encyclopedia - Chrysocolla
Chrysocolla (hydrated copper silicate) is a mineral, CuSiO3·nH2O. It is of secondary origin and forms in the oxidation zones of copper o...   » Read the article

Encyclopedia - Alabaster: Encyclopedia - Alabaster
Alabaster (sometimes called satin spar) is a name applied to varieties of two distinct minerals: gypsum (a hydrous sulfate of calcium) an...   » Read the article

Encyclopedia - Amethyst: Encyclopedia - Amethyst
Amethyst is a violet or purple variety of quartz often used as an ornament. The name is generally said to be derived from the Greek a, "n...   » Read the article

Encyclopedia - Agate: Encyclopedia - Agate
Agate is a term applied not to a distinct mineral species, but to an aggregate of various forms of silica, chiefly chalcedony. According ...   » Read the article

Encyclopedia - Barite: Encyclopedia - Barite
Barite (BaSO4) is a mineral consisting of barium sulfate. It is generally white or colorless, and is the main source of barium. Baryte is...   » Read the article

Encyclopedia - Azurite: Encyclopedia - Azurite
Azurite is a carbonate mineral with chemical composition Cu3(CO3)2(OH)2, (copper carbonate hydroxide). Azurite is often found in associat...   » Read the article

Encyclopedia - Apatite: Encyclopedia - Apatite
Apatite is a group of phosphate minerals, usually referring to: hydroxylapatite, fluorapatite, and chlorapatite, named for high concentra...   » Read the article

Encyclopedia - Wollastonite: Encyclopedia - Wollastonite
Wollastonite is a calcium inosilicate mineral (CaSiO3) that may contain small amounts of iron, magnesium, and manganese substituting for ...   » Read the article

Encyclopedia - Vivianite: Encyclopedia - Vivianite
Vivianite Fe3(PO4)2·8(H2O), hydrated iron phosphate, is a secondary mineral found in a number of geological environments. Usually found ...   » Read the article

Encyclopedia - Calaverite: Encyclopedia - Calaverite
Calaverite, or gold telluride, is an uncommon telluride of gold; it is a metallic mineral. It was first discovered in Calaveras County, C...   » Read the article

Encyclopedia - Uvarovite: Encyclopedia - Uvarovite
Uvarovite is a chromium bearing garnet: Ca3Cr2(SiO4)3. It was discovered in 1832 and is named after Count Sergei Semenovitch Uvarov (1765...   » Read the article

Encyclopedia - Quartz: Encyclopedia - Quartz
Quartz is the most abundant mineral in the Earth's continental crust. It has a hexagonal crystal structure made of trigonal crystallized ...   » Read the article

Encyclopedia - Plagioclase: Encyclopedia - Plagioclase
Plagioclase feldspars are a very important group of igneous rock forming tectosilicate minerals. Plagioclase comprises a solid solution s...   » Read the article

Encyclopedia - Ruby: Encyclopedia - Ruby
Ruby is a red gemstone, a variety of the mineral corundum (aluminium oxide) in which the color is caused mainly by chromium. Its name ori...   » Read the article

Encyclopedia - Aquamarine: Encyclopedia - Aquamarine
Aquamarine (Lat. aqua marina, "water of the sea") is a gemstone-quality transparent variety of beryl, having a delicate blue or bluish-gr...   » Read the article

Encyclopedia - Mineral: Encyclopedia - Mineral
This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). Mineral...   » Read the article

Encyclopedia - Gemstone: Encyclopedia - Gemstone
A gemstone is a mineral, rock (as in lapis lazuli) or petrified material that when cut or faceted and polished is collectible or can be u...   » Read the article

Encyclopedia - Zircon: Encyclopedia - Zircon
Zircon is a mineral belonging to the group of nesosilicates. Its chemical formula is ZrSiO4. Hafnium is almost always present ranging fro...   » Read the article

Encyclopedia - Zoisite: Encyclopedia - Zoisite
Zoisite is a calcium aluminium hydroxy sorosilicate belonging to the epidote group of minerals. Zoisite is named after Austrian scientist...   » Read the article

Encyclopedia - Uraninite: Encyclopedia - Uraninite
Uraninite is a uranium-rich mineral with a composition that is largely UO2 (uranium oxide), but which also contains UO3 and oxides of lea...   » Read the article

Encyclopedia - Alluvial Deposit: Encyclopedia - Alluvial Deposit
An alluvial deposit is an accumulation of alluvium (sediment), sometimes containing valuable ore and gemstones, or simply consisting of g...   » Read the article

Encyclopedia - Desert: Encyclopedia - Desert
In geography, a desert is a landscape form or region that receives little precipitation - less than 250 mm per year. Deserts have a reput...   » Read the article

Encyclopedia - Sodalite: Encyclopedia - Sodalite
Sodalite is a rare, rich royal blue mineral widely enjoyed as an ornamental stone. Although massive sodalite samples are opaque, crystals...   » Read the article

Encyclopedia - Cinnabar: Encyclopedia - Cinnabar
Cinnabar (German Zinnober), sometimes written cinnabarite, is a name applied to red mercury(II) sulfide (HgS), or native vermilion, the c...   » Read the article

Encyclopedia - Uk Miners' Strike 1984-1985: Encyclopedia - Uk Miners' Strike 1984-1985
The miners' strike of 1984-5 was a major piece of industrial action affecting the British coal industry. It was a defining event in the h...   » Read the article

Encyclopedia - Calcite: Encyclopedia - Calcite
The carbonate mineral calcite is a calcium carbonate corresponding to the formula CaCO3 and is one of the most widely distributed mineral...   » Read the article

Encyclopedia - Emerald: Encyclopedia - Emerald
Emerald (Be3Al2SiO6) is a variety of the mineral beryl, colored green by trace amounts of chromium and sometimes iron. It is highly prize...   » Read the article

Encyclopedia - Jasper: Encyclopedia - Jasper
Jasper is an opaque, impure variety of quartz that is usually red, yellow or brown in color. This mineral breaks with a smooth surface, a...   » Read the article

Encyclopedia - Aragonite: Encyclopedia - Aragonite
Aragonite is a carbonate mineral, a polymorph of the mineral calcite, both having the chemical composition CaCO3. Its structure differs f...   » Read the article

Encyclopedia - Hematite: Encyclopedia - Hematite
Hematite (AE) or haematite (BE) is the mineral form of Iron (III) oxide, (Fe2O3), one of several iron oxides. The ore sometimes contains ...   » Read the article

Encyclopedia - Beryl: Encyclopedia - Beryl
The mineral beryl is a beryllium aluminium cyclosilicate with the chemical formula Be3Al2(SiO3)6. The hexagonal crystals of beryl may be ...   » Read the article

Encyclopedia - Amphibole: Encyclopedia - Amphibole
For the logical fallacy, see Amphibology. Amphibole defines an important group of dark-colored rock-forming inosilicate minerals composed...   » Read the article

Encyclopedia - Sodium Bicarbonate: Encyclopedia - Sodium Bicarbonate
SI units were used where possible. Unless otherwise stated, standard conditions were used. Disclaimer and references Sodium bicarbonate (...   » Read the article

Encyclopedia - Chalk: Encyclopedia - Chalk
Chalk is a soft, white, porous form of limestone composed of the mineral calcium carbonate. It is relatively resistant to erosion and slu...   » Read the article

Encyclopedia - Sapphire: Encyclopedia - Sapphire
Sapphire is the single-crystal form of aluminium oxide (Al2O3), a mineral known as corundum. It can be found naturally as gemstones or ma...   » Read the article

Encyclopedia - Quarry: Encyclopedia - Quarry
A quarry is a type of open-pit mine from which rock or minerals are extracted. Quarries are generally used for extracting building materi...   » Read the article

Encyclopedia - Antigorite: Encyclopedia - Antigorite
Antigorite is a monoclinic mineral from the kaolinite-serpentine group. It is a polymorph of clinochrysotile, lizardite, orthochrysotile ...   » Read the article

Encyclopedia - Fluorite: Encyclopedia - Fluorite
Fluorite (also called fluor-spar) is a mineral composed of calcium fluoride, CaF2. It is an isometric mineral with a cubic habit, though...   » Read the article

Encyclopedia - Olivine: Encyclopedia - Olivine
The mineral olivine is a magnesium iron silicate with the formula (Mg,Fe)2SiO4 in which the ratio of magnesium and iron varies between th...   » Read the article

Encyclopedia - Chlorite Group: Encyclopedia - Chlorite Group
Chlorite is a group of phyllosilicate minerals often classified as clays. Chlorites can be described by the following four endmembers bas...   » Read the article

Encyclopedia - Blue Amber: Encyclopedia - Blue Amber
Blue Amber is a rare coloration of amber. It most commonly is found in the Dominican Republic and well regarded by collectors for its val...   » Read the article

Encyclopedia - Clay: Encyclopedia - Clay
Clay is a generic term for an aggregate of hydrous silicate particles less than 4 μm (micrometres) in diameter. Clay consists of a varie...   » Read the article

Encyclopedia - Opal: Encyclopedia - Opal
The mineraloid opal is amorphous SiO2·nH2O; hydrated silicon dioxide, the water content sometimes being as high as 20%. Opal ranges from...   » Read the article

Encyclopedia - Mineral: Encyclopedia Ii - Mineral - Mineral Definition And Classification
To be classified as a "true" mineral, a substance must be a solid and have a crystal structure. It must also be an inorganic, naturally-o...   » Read the article

Encyclopedia - Desert: Encyclopedia Ii - Desert - Mineral Resources
Some mineral deposits are formed, improved, or preserved by geologic processes that occur in arid lands as a consequence of climate. Grou...   » Read the article

Encyclopedia - Gemstone: Encyclopedia Ii - Gemstone - Gemstone List
There are over 130 species of minerals that have been cut into gems with 50 species in common use. These include: Agate Alexandrite and ...   » Read the article

Encyclopedia - Zircon: Encyclopedia Ii - Zircon - Properties
Zircon is a remarkable mineral, if only for its almost ubiquitous presence in the crust of Earth. It is found in igneous rocks (as primar...   » Read the article

Encyclopedia - Quartz: Encyclopedia Ii - Quartz - Varieties
Quartz is one of the world's most common crustal minerals and goes by a bewildering array of different names. The most important distinct...   » Read the article

Encyclopedia - Talc: Encyclopedia Ii - Talc - Safety
Several studies have established preliminary links between talc and pulmonary issues [1], ovarian cancer [2], and lung cancer [3] [4]. Th...   » Read the article

Encyclopedia - Searles Lake: Encyclopedia Ii - Searles Lake - Mineralogy
Searles Lake is a huge resource of sodium and potassium minerals of the carbonate, sulfate, borate and halide classes of mineralogy. The ...   » Read the article

Encyclopedia - Cinnabar: Encyclopedia Ii - Cinnabar - Of Note
Cinnabar is associated with the element mercury, but contrary to popular belief, is safe to handle. This article incorporates text from t...   » Read the article

Encyclopedia - Xenotime: Encyclopedia Ii - Xenotime - Occurrence
Occurring as a minor accessory mineral, xenotime is found in pegmatites and other igneous rocks, as well as gneisses rich in mica and qua...   » Read the article

Encyclopedia - Sodalite: Encyclopedia Ii - Sodalite - Occurrence
Occurring typically in massive form, sodalite is found as vein fillings in plutonic igneous rocks such as nepheline syenites. It is assoc...   » Read the article

Encyclopedia - Alabaster: Encyclopedia Ii - Alabaster - Gypsum Alabaster
In the present day, when the term "alabaster" is used without any qualification, it invariably means a fine-grained variety of gypsum. Th...   » Read the article

Encyclopedia - Sodalite: Encyclopedia Ii - Sodalite - Properties
A light, relatively hard yet fragile mineral, sodalite is named after its sodium content; in mineralogy it may be classed as a feldspatho...   » Read the article

Encyclopedia - Desert: Encyclopedia Ii - Desert - List Of Deserts
Desert - Americas. Atacama desert in Chile Mojave, Great Basin, Sonoran, and Chihuahuan See also: List of North American deserts Des...   » Read the article

Encyclopedia - Amethyst: Encyclopedia Ii - Amethyst - Amethyst In Folklore And Astrology
Amethyst is the birthstone associated with February. It is also associated with the constellations of Pisces, Aries (especially the viole...   » Read the article

Encyclopedia - Uk Miners' Strike 1984-1985: Encyclopedia Ii - Uk Miners' Strike 1984-1985 - Strike In Artistic Depictions
The UK miners' strike was the background for the critically acclaimed 2000 film Billy Elliot. Several scenes powerfully depict the chaos ...   » Read the article

Encyclopedia - Uk Miners' Strike 1984-1985: Encyclopedia Ii - Uk Miners' Strike 1984-1985 - History
In 1984, the National Coal Board (the UK Public Body which controlled coal mining) announced that an agreement reached after the 1974 min...   » Read the article

Encyclopedia - Quartz: Encyclopedia Ii - Quartz - History
The name "quartz" comes from the German "Quarz", which is of Slavic origin. Quartz is the most common material identified as the mystical...   » Read the article

Encyclopedia - Beryl: Encyclopedia Ii - Beryl - Applications
Massive beryl is a primary ore of the metal beryllium. ... See also:Beryl, Beryl - Varieties, Beryl - Deposits, Beryl - Applications   » Read the article

Encyclopedia - Alabaster: Encyclopedia Ii - Alabaster - Calcite Alabaster
This substance, the "alabaster" of the Bible, is often termed Oriental alabaster, since the early examples came from the Far East. The Gr...   » Read the article

Encyclopedia - Desert: Encyclopedia Ii - Desert - Desert Features
Sand covers only about 20 percent of Earth's deserts. Most of the sand is in sand sheets and sand seas—vast regions of undulating dunes...   » Read the article

Encyclopedia - Desert: Encyclopedia Ii - Desert - Desert Features
Sand covers only about 20 percent of Earth's deserts. Most of the sand is in sand sheets and sand seas—vast regions of undulating dunes...   » Read the article

Encyclopedia - Uk Miners' Strike 1984-1985: Encyclopedia Ii - Uk Miners' Strike 1984-1985 - After The Strike
The effect of the strike has been long and bitter for many areas that depended on coal. Enduring a year on strike pay forced many miners ...   » Read the article

Encyclopedia - Jasper: Encyclopedia Ii - Jasper - Types Of Jasper
Jasper can appear as an opaque rock of almost any color due to mineral impurities. More usually, jasper exhibits one or more type of patt...   » Read the article

Encyclopedia - Calcite: Encyclopedia Ii - Calcite - Properties
Calcite crystals are hexagonal-rhombohedral, though actual calcite rhombohedrons are rare as natural crystals. However, they show a remar...   » Read the article

Encyclopedia - Agate: Encyclopedia Ii - Agate - Formation And Characteristics
Most agates occur as nodules in eruptive rocks or ancient lavas where they represent cavities originally produced by the disengagement of...   » Read the article

Encyclopedia - Amphibole: Encyclopedia Ii - Amphibole - Amphibole Groups
Orthorhombic Series Anthophyllite (Mg,Fe)7Si8O22(OH)2 Monoclinic Series Tremolite Ca2Mg5Si8O22(OH)2 Actinolite Ca2(Mg,Fe)5Si8O22(OH)2 ...   » Read the article

Encyclopedia - Beryl: Encyclopedia Ii - Beryl - Deposits
Beryl is found most commonly in granitic pegmatites, but also occurs in mica schists in the Ural Mountains and is often associated with t...   » Read the article

Encyclopedia - Shale: Encyclopedia Ii - Shale - Formation
The fine particles that compose shale can remain suspended in water long after the larger and denser particles of sand have deposited out...   » Read the article

Encyclopedia - Sapphire: Encyclopedia Ii - Sapphire - Synthetic Sapphire For Non-gemstone Applications
Synthetic sapphire crystals can be grown in cylindrical crystal ingots of large size, up to many inches in diameter. As well as gemstone ...   » Read the article

Encyclopedia - Sapphire: Encyclopedia Ii - Sapphire - Sapphire Gems
Sapphire is any gemstone-quality corundum. (The red variety of corundum is also known as ruby.) When color is not specified, sapphire ref...   » Read the article

Encyclopedia - Desert: Encyclopedia Ii - Desert - Types Of Desert
Most classifications rely on some combination of the number of days of rainfall, the total amount of annual rainfall, temperature, humidi...   » Read the article

Encyclopedia - Metamorphic Rock: Encyclopedia Ii - Metamorphic Rock - Metamorphic Minerals
Metamorphic minerals are those that form only at the high temperatures and pressures associated with the process of metamorphism. These m...   » Read the article

Encyclopedia - Metamorphic Rock: Encyclopedia Ii - Metamorphic Rock - Foliation
The layering within metamorphic rocks is called foliation (derived from the Latin word folia, meaning "leaves"), and it occurs when a str...   » Read the article

Encyclopedia - Agate: Encyclopedia Ii - Agate - Agate Beliefs
In Islam, agates are deemed to be very precious stones. According to tradition, the wearer of an agate ring, for example, is believed to ...   » Read the article

Encyclopedia - Metamorphic Rock: Encyclopedia Ii - Metamorphic Rock - Types Of Metamorphism
Contact metamorphism is the name given to the changes that take place when magma is injected into the surrounding solid rock (country roc...   » Read the article

Encyclopedia - Agate: Encyclopedia Ii - Agate - Types Of Agate
A Mexican agate, showing only a single eye, has received the name of "cyclops agate." Included matter of a green, golden, red, black or o...   » Read the article

Encyclopedia - Gold Chalcogenides: Encyclopedia Ii - Gold Chalcogenides - Gold Sulfides
Au2S is metastable, but mixed silver-gold sulfides like AgAuS do exist. No studies of gold polonides have been conducted yet, as polonium...   » Read the article

Encyclopedia - Fluorite: Encyclopedia Ii - Fluorite - Occurrence
Fluorite may occur as a vein deposit, especially with metallic minerals, where it often forms a part of the gangue (the worthless "host-r...   » Read the article

Encyclopedia - Chlorite Group: Encyclopedia Ii - Chlorite Group - Chlorite Structure
The typical general formula is: (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6. This formula emphasises the structure of the group. Chlorites ha...   » Read the article

Encyclopedia - Chlorite Group: Encyclopedia Ii - Chlorite Group - Members Of The Chlorite Group:
Clinoclore, penninite, and chamosite are the most common varieties. Several other sub-varieties have been described. The name chlorite is...   » Read the article

Encyclopedia - Dolomite: Encyclopedia Ii - Dolomite - The Dolomite Problem
There is significant uncertainty regarding the cause of dolomite formation. Vast deposits are present in the geological record, but the m...   » Read the article

Encyclopedia - Sapphire: Encyclopedia Ii - Sapphire - Synthetic Sapphire For Non-gemstone Applications
Synthetic sapphire crystals can be grown in cylindrical crystal ingots of large size, up to many inches in diameter. As well as gemstone ...   » Read the article

Encyclopedia - Opal: Encyclopedia Ii - Opal - Synthetic Opal
As well as occurring naturally, opals of all varieties have been synthesized experimentally and commercially. The resulting material is d...   » Read the article

Encyclopedia - Blue Amber: Encyclopedia Ii - Blue Amber - Origin
It is not fully understood what causes the blue coloration. One theory links the rare properties to the occurrence of volcanic ash or dus...   » Read the article

Encyclopedia - Sapphire: Encyclopedia Ii - Sapphire - Sapphire Gems
Sapphire is any gemstone-quality corundum that is not red. (The red variety of corundum is also known as ruby.) When color is not specifi...   » Read the article

Encyclopedia - Clay: Encyclopedia Ii - Clay - Historical And Modern Uses Of Clay
Clays are heavy in texture yet soft to the touch. Clay is a malleable substance when wet, which means it can be shaped easily with the ha...   » Read the article

Encyclopedia - Opal: Encyclopedia Ii - Opal - Common Opal
Besides the gemstone varieties that show a play of color, there are other kinds of common opal such as the milk opal, milky bluish to gre...   » Read the article

Encyclopedia - Opal: Encyclopedia Ii - Opal - Sources Of Opal
About 95% of the world's opal comes from Australia. In particular, the town of Coober Pedy in South Australia is a major source. Common, ...   » Read the article

Encyclopedia - Blueschist: Encyclopedia Ii - Blueschist - Blueschist Facies
Blueschist Facies is determined by the particular T-P conditions required to metamorphose basalt to form Blueschist. Felsic rocks and pel...   » Read the article