Pinalite
Encyclopedia
Pinalite is a rare lead
tungstate
–chloride
mineral with formula: Pb3WO5Cl2.
Pinalite crystallizes in the orthorhombic crystal system
. The orthorhombic system is described as having three crystallographic axes of unequal lengths, normally referred to as c (the longest axes), b (the second longest axes), and a (the smallest axes). These axes all have corresponding angles of 90 degrees. Pinalite belongs to the biaxial optical class, and is negative. The main difference between biaxial and axial crystals is that biaxial crystals have two optic axes.
Pinalite's structure is significant in that it is one of a kind. It is therefore important in seeing how the structures in new lead oxyhalides (containing square pyramids incorporated into sheets) are arranged. It's structure contains an extra oxygen, which therefore has a very small amount of free space and consequently protrudes into neighboring layers. The oxygen then pushes aside the chlorine atoms, leaving almost no room for the lead to occupy. This is of interest to geologists for it is such a rare occurrence of structure seen only in pinalite and its barium
analog. Therefore, it could be of use to structuralists to see how this mineral was formed. Experiments have been done, using lead oxyhalides, to see the reason and sequence of events in which this mineral is executed.
, Mammoth District, Pinal Co.
, Arizona
, USA, and was named for the location county. Pinalite has otherwise only been seen in the Grand Reef mine, near Klondyke
in the Santa Teresa Mountains
in Graham County, Arizona
, so is therefore found around orogenic activity.
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
tungstate
Tungstate
In chemistry a tungstate is a compound that contains an oxoanion of tungsten or is a mixed oxide containing tungsten. The simplest tungstate ion is WO42−, "orthotungstate"...
–chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...
mineral with formula: Pb3WO5Cl2.
Pinalite crystallizes in the orthorhombic crystal system
Crystal system
In crystallography, the terms crystal system, crystal family, and lattice system each refer to one of several classes of space groups, lattices, point groups, or crystals...
. The orthorhombic system is described as having three crystallographic axes of unequal lengths, normally referred to as c (the longest axes), b (the second longest axes), and a (the smallest axes). These axes all have corresponding angles of 90 degrees. Pinalite belongs to the biaxial optical class, and is negative. The main difference between biaxial and axial crystals is that biaxial crystals have two optic axes.
Pinalite's structure is significant in that it is one of a kind. It is therefore important in seeing how the structures in new lead oxyhalides (containing square pyramids incorporated into sheets) are arranged. It's structure contains an extra oxygen, which therefore has a very small amount of free space and consequently protrudes into neighboring layers. The oxygen then pushes aside the chlorine atoms, leaving almost no room for the lead to occupy. This is of interest to geologists for it is such a rare occurrence of structure seen only in pinalite and its 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...
analog. Therefore, it could be of use to structuralists to see how this mineral was formed. Experiments have been done, using lead oxyhalides, to see the reason and sequence of events in which this mineral is executed.
Discovery and occurrence
Pinalite was first discovered in 1989 in the St. Anthony deposit, TigerTiger, Arizona
Tiger is a ghost town in Pinal County in the U.S. state of Arizona. The town was settled as Schultz around 1881 in what was then the Arizona Territory, then later reestablished as Tiger after World War I.-History:...
, Mammoth District, Pinal Co.
Pinal County, Arizona
-2010:Whereas according to the 2010 U.S. Census Bureau:*72.4% White*4.6% Black*5.6% Native American*1.7% Asian*0.4% Native Hawaiian or Pacific Islander*3.8% Two or more races*11.5% Other races*28.5% Hispanic or Latino -2000:...
, Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, USA, and was named for the location county. Pinalite has otherwise only been seen in the Grand Reef mine, near Klondyke
Klondike, Yukon
The Klondike is a region of the Yukon in northwest Canada, east of the Alaska border. It lies around the Klondike River, a small river that enters the Yukon from the east at Dawson....
in the Santa Teresa Mountains
Santa Teresa Mountains
The Santa Teresa Mountains are located in western Graham County, Arizona, within the Coronado National Forest and within the Santa Teresa Wilderness.-External links:*...
in Graham County, Arizona
Graham County, Arizona
-2010:Whereas according to the 2010 U.S. Census Bureau:*72.1% White*1.8% Black*14.4% Native American*0.5% Asian*0.1% Native Hawaiian or Pacific Islander*2.8% Two or more races*8.3% Other races*30.4% Hispanic or Latino -2000:...
, so is therefore found around orogenic activity.