Parisite
Encyclopedia
Parisite is a rare mineral
consisting of cerium
, lanthanum
and calcium
fluoro
-carbonate
, Ca
(Ce
,La
)2(C
O
3)3F
2. Parisite is mostly parisite-(Ce), but when neodymium
is present in the structure the mineral becomes parisite-(Nd).
It is found only as crystal
s, which belong to the trigonal or monoclinic pseudo-hexagonal system and usually have the form of acute double pyramid
s terminated by the basal planes; the face
s of the hexagonal pyramids are striated horizontally, and parallel to the basal plane there is a perfect cleavage
. The crystals are hair-brown in color and are translucent. The hardness
is 4.5 and the specific gravity
is 4.36. Light which has traversed a crystal of parisite exhibits a characteristic absorption spectrum.
At first, the only known occurrence of this mineral was in the famous emerald
mine
at Muzo in Colombia
, South America
, where it was found by J.J. Paris, who rediscovered and worked the mine in the early part of the 19th century; here it is associated with emerald in a bituminous limestone
of Cretaceous
age.
Closely allied to parisite, and indeed first described as such, is a mineral from the nepheline
-syenite
district of Julianehaab in south Greenland
. To this the name synchysite has been given. The crystals are rhombohedral (as distinct from hexagonal; they have the composition CeFCa(CO3)2, and specific gravity
of 2.90. At the same locality there is also found a barium
-parisite, which differs from the Colombian parisite in containing barium in place of calcium, the formula being (CeF)2Ba
(CO3)3: this is named cordylite on account of the club-shaped form of its hexagonal crystals. Bastnasite
is a cerium lanthanum and neodymium fluoro-carbonate (CeF)CO3, from Bastnas, near Riddarhyttan, in Vestmanland, Sweden
, and the Pikes Peak
region in Colorado
, U.S.A.
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
consisting of cerium
Cerium
Cerium is a chemical element with the symbol Ce and atomic number 58. It is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet . Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight...
, lanthanum
Lanthanum
Lanthanum is a chemical element with the symbol La and atomic number 57.Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table and is the first element of the lanthanide series. It is found in some rare-earth minerals, usually in combination with cerium and...
and calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
fluoro
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...
-carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
, Ca
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
(Ce
Cerium
Cerium is a chemical element with the symbol Ce and atomic number 58. It is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet . Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight...
,La
Lanthanum
Lanthanum is a chemical element with the symbol La and atomic number 57.Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table and is the first element of the lanthanide series. It is found in some rare-earth minerals, usually in combination with cerium and...
)2(C
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
3)3F
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...
2. Parisite is mostly parisite-(Ce), but when neodymium
Neodymium
Neodymium is a chemical element with the symbol Nd and atomic number 60. It is a soft silvery metal that tarnishes in air. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach. It is present in significant quantities in the ore minerals monazite and bastnäsite...
is present in the structure the mineral becomes parisite-(Nd).
It is found only as crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
s, which belong to the trigonal or monoclinic pseudo-hexagonal system and usually have the form of acute double pyramid
Pyramid
A pyramid is a structure whose outer surfaces are triangular and converge at a single point. The base of a pyramid can be trilateral, quadrilateral, or any polygon shape, meaning that a pyramid has at least three triangular surfaces...
s terminated by the basal planes; the face
Face
The face is a central sense organ complex, for those animals that have one, normally on the ventral surface of the head, and can, depending on the definition in the human case, include the hair, forehead, eyebrow, eyelashes, eyes, nose, ears, cheeks, mouth, lips, philtrum, temple, teeth, skin, and...
s of the hexagonal pyramids are striated horizontally, and parallel to the basal plane there is a perfect cleavage
Cleavage (crystal)
Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite crystallographic structural planes. These planes of relative weakness are a result of the regular locations of atoms and ions in the crystal, which create smooth repeating surfaces that are visible both in the...
. The crystals are hair-brown in color and are translucent. The hardness
Mohs scale of mineral hardness
The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and is one of several definitions of hardness in...
is 4.5 and the specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
is 4.36. Light which has traversed a crystal of parisite exhibits a characteristic absorption spectrum.
At first, the only known occurrence of this mineral was in the famous emerald
Emerald
Emerald is a variety of the mineral beryl colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the 10 point Mohs scale of mineral hardness...
mine
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
at Muzo in Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
, South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, where it was found by J.J. Paris, who rediscovered and worked the mine in the early part of the 19th century; here it is associated with emerald in a bituminous limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
of Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
age.
Closely allied to parisite, and indeed first described as such, is a mineral from the nepheline
Nepheline
Nepheline, also called nephelite , is a feldspathoid: a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites...
-syenite
Syenite
Syenite is a coarse-grained intrusive igneous rock of the same general composition as granite but with the quartz either absent or present in relatively small amounts Syenite is a coarse-grained intrusive igneous rock of the same general composition as granite but with the quartz either absent or...
district of Julianehaab in south Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
. To this the name synchysite has been given. The crystals are rhombohedral (as distinct from hexagonal; they have the composition CeFCa(CO3)2, and specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
of 2.90. At the same locality there is also found a barium
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
-parisite, which differs from the Colombian parisite in containing barium in place of calcium, the formula being (CeF)2Ba
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
(CO3)3: this is named cordylite on account of the club-shaped form of its hexagonal crystals. Bastnasite
Bastnasite
The mineral bastnäsite is one of a family of three carbonate-fluoride minerals, which includes bastnäsite- with a formula of CO3F, bastnäsite- with a formula of CO3F, and bastnäsite- with a formula of CO3F. Most bastnäsite is bastnäsite-, and cerium is by far the most common of the rare earths in...
is a cerium lanthanum and neodymium fluoro-carbonate (CeF)CO3, from Bastnas, near Riddarhyttan, in Vestmanland, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
, and the Pikes Peak
Pikes Peak
Pikes Peak is a mountain in the Front Range of the Rocky Mountains, west of Colorado Springs, Colorado, in El Paso County in the United States of America....
region in Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
, U.S.A.