Brockite is a rare earth

phosphate mineral Phosphate minerals contain the tetrahedrally coordinated phosphate (PO43−) anion along sometimes with arsenate (AsO43−) and vanadate (VO43−) substitutions, and chloride (Cl−), fluoride (F−), and hydroxide (OH−) anions that also fit i ...

with formula: (Ca,Th,Ce)PO₄·H₂O. It crystallizes in the

hexagonal In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A '' regular hexagon'' has ...

system in the

chiral Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from ...

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchan ...

180 or its

enantiomorph In geometry, a figure is chiral (and said to have chirality) if it is not identical to its mirror image, or, more precisely, if it cannot be mapped to its mirror image by rotations and translations alone. An object that is not chiral is said to ...

181. It is typically granular to massive with only rare occurrence of stubby crystals. It is

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...

due to the

thorium Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high me ...

content.

Discovery and occurrence

Brockite was first described in 1962 for an occurrence in the Bassick Mine area, Querida,

Wet Mountains The Wet Mountains are a small mountain range in southern Colorado, named for the amount of snow they receive in the winter as compared to the dried Great Plains to the east. They are a sub-range of the Sangre de Cristo Mountains, in the southern R ...

Custer County, Colorado Custer County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 4,704. The county seat is Westcliffe. History Custer County was created by the Colorado legislature on March 9, 1877, out of the southe ...

, US. It was named for Maurice R. Brock, of the

U.S. Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and ...

. Brockite occurs in

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

and granite

pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ...

as an accessory mineral. Associated minerals include

monazite Monazite is a primarily reddish-brown phosphate mineral that contains rare-earth elements. Due to variability in composition, monazite is considered a group of minerals. The most common species of the group is monazite-(Ce), that is, the cerium- ...

, bastnasite,

xenotime Xenotime is a rare-earth phosphate mineral, the major component of which is yttrium orthophosphate ( Y P O4). It forms a solid solution series with chernovite-(Y) ( Y As O4) and therefore may contain trace impurities of arsenic, as well as sili ...

thorite Thorite, (Th,U)SiO4, is a rare nesosilicate of thorium that crystallizes in the tetragonal system and is isomorphous with zircon and hafnon. It is the most common mineral of thorium and is nearly always strongly radioactive. It was named in 1829 to ...

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of the r ...

apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ions, respectively, in the crystal. The formula of the admixture of the three most common e ...

rutile Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer Polymorphism (materials science), polymorphs of TiO2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest ...

and

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...

References

Phosphate minerals Hexagonal minerals Minerals in space group 180 or 181 {{phosphate-mineral-stub