Jerrygibbsite
Encyclopedia
Jerrygibbsite is a rare silicate mineral with chemical formula: (Mn,Zn)9(SiO4)4(OH)2. Jerrygibbsite was originally discovered by Pete J. Dunn in 1984, who named it after mineralogist Gerald V. Gibbs. It has only been reported from the type locality
of Franklin Furnace
, New Jersey
, United States, and in Namibia
's Otjozondjupa
region. Jerrygibbsite is member of the leucophoenite family of the humite group
. It is always found with these two minerals. It is a dimorph
of sonolite.
analysis of a sample previously assumed to be leucophoenicite. All samples found of jerrygibbsite are impure. All are incorporated within leucophoenicite, many by mixed layering, and tend to be found with many manganese
humites such as sonolite. Physical properties are similar to those of leucophoenicite and sonolite, including hardness, coloring, and density.
, magnesium
, calcium
or water
. The idealized formula is Mn9(SiO4)4(OH)2 which is the same ideal formula as sonolite, a member of the humite group. Jerrygibbsite has been found to be dimorphous with sonolite.
mine in Franklin, New Jersey, and in the Kombat Mines in Namibia
. Most of the minerals in the humite group have been found only here, as well as leucophoenicite. Jerrygibbsite has been found to occur in contact with willemite
, zincite, and sonolite in an uncommon assemblage. Jerrygibbsite typically occurs as a massive mineral in interlocking anhedral crystals, up to 0.5 mm × 2.0 mm, which display a typical metamorphic texture. Subsequent finds from the Namibia mines were of two different textures.
of 0.017. In thin section
, jerrygibbsite appears light pink. The crystal structure described by Kato is the equivalent of a unit-cell-twinned sonolite in which the cells are related by a b/4 glide plane.
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
of Franklin Furnace
Franklin Furnace
Franklin Furnace, also known as the Franklin Mine, is a famous mineral location for rare zinc, iron, manganese minerals in old mines in Franklin, New Jersey, USA. This locale produced more species of minerals and more different fluorescent minerals than any other location...
, New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
, United States, and in Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
's Otjozondjupa
Otjozondjupa
Otjozondjupa region is one of the thirteen regions of Namibia. An outstanding landmark within this region is the Waterberg Plateau Park. Administration offices are based in Otjiwarongo which is the largest town in the region....
region. Jerrygibbsite is member of the leucophoenite family of the humite group
Humite (mineral group)
The humite group is a group of nesosilicates with the general formula Anm2.When A is predominantly magnesium we have the humite subgroup:*norbergite, Mg32*chondrodite, 522*humite, 732...
. It is always found with these two minerals. It is a dimorph
Polymorphism (materials science)
Polymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to chemical elements...
of sonolite.
Discovery
The mineral jerrygibbsite was discovered in 1984 by Pete Dunn while conducting an X-ray spectrographicX-ray spectroscopy
X-ray spectroscopy is a gathering name for several spectroscopic techniques for characterization of materials by using x-ray excitation.-Characteristic X-ray Spectroscopy:...
analysis of a sample previously assumed to be leucophoenicite. All samples found of jerrygibbsite are impure. All are incorporated within leucophoenicite, many by mixed layering, and tend to be found with many manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
humites such as sonolite. Physical properties are similar to those of leucophoenicite and sonolite, including hardness, coloring, and density.
Composition
The formula for jerrygibbsite is (Mn,Zn)9(SiO4)4(OH)2, although it often contains impurities of ironIron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
, 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...
or water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
. The idealized formula is Mn9(SiO4)4(OH)2 which is the same ideal formula as sonolite, a member of the humite group. Jerrygibbsite has been found to be dimorphous with sonolite.
Geologic occurrence
Jerrygibbsite has been found only in the Franklin FurnaceFranklin Furnace
Franklin Furnace, also known as the Franklin Mine, is a famous mineral location for rare zinc, iron, manganese minerals in old mines in Franklin, New Jersey, USA. This locale produced more species of minerals and more different fluorescent minerals than any other location...
mine in Franklin, New Jersey, and in the Kombat Mines in Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
. Most of the minerals in the humite group have been found only here, as well as leucophoenicite. Jerrygibbsite has been found to occur in contact with willemite
Willemite
Willemite is a zinc silicate mineral and a minor ore of zinc. It is highly fluorescent under shortwave ultraviolet light.It occurs in all different colors in daylight, in fibrous masses, solid brown masses , and apple green gemmy masses.It was discovered in 1830 and named after William I of the...
, zincite, and sonolite in an uncommon assemblage. Jerrygibbsite typically occurs as a massive mineral in interlocking anhedral crystals, up to 0.5 mm × 2.0 mm, which display a typical metamorphic texture. Subsequent finds from the Namibia mines were of two different textures.
Physical properties
Jerrygibbsite, in pure form, is a violet-pink mineral with a light pink streak. It has a calculated density of 4.045 g/cm³, and a tested density of 4.00 g/cm³, agreeing favorably, since measurements used to test density have few significant figures. It has a hardness of about 5.5, that of a knife blade. The general luster is vitreous, or shiny. Crystals are generally transparent to translucent. Crystals are not luminescent or fluorescent. Jerrygibbsite forms orthorhombic crystals with an imperfect cleavage along the {001} plane, which can be seen by opaque lamellae alternating with the transparent jerrygibbsite. Optically, jerrygibbsite is negative biaxial with 2V = 72˚ and a maximum birefringenceBirefringence
Birefringence, or double refraction, is the decomposition of a ray of light into two rays when it passes through certain anisotropic materials, such as crystals of calcite or boron nitride. The effect was first described by the Danish scientist Rasmus Bartholin in 1669, who saw it in calcite...
of 0.017. In thin section
Thin section
In optical mineralogy and petrography, a thin section is a laboratory preparation of a rock, mineral, soil, pottery, bones, or even metal sample for use with a polarizing petrographic microscope, electron microscope and electron microprobe. A thin sliver of rock is cut from the sample with a...
, jerrygibbsite appears light pink. The crystal structure described by Kato is the equivalent of a unit-cell-twinned sonolite in which the cells are related by a b/4 glide plane.