Franklin Terms and Definitions

Mineral collectors who specialize in Franklin and Sterling Hill have their own unique vocabulary, from jargon, to historical references, and sometimes outdated terms. Some terms relate to specific minerals or mineral characteristics, some to the local geology, and some to locations in and around the "Franklin mining district."

Franklin Mineral Terms
Geological Terms
Location Terms

Franklin Mineral Terms
TermDefinition   
Black oreThis ore contains "black" willemite which is colored by microscopic franklinite inclusions; it is common at Sterling Hill, but uncommon at Franklin. 1001
Brown oreThis ore contains willemite colored brown from franklinite inclusions. 1025
Buckshot-oreA term used for distinctly granular franklinite-bearing ore. Local mythology is that the hard iron-oxide franklinite crystal grains that weathered out of the ore were used to reload shotgun shells. 1009
CalcozinciteIs a material comprised of admixed yellow and red zincite and compact calcite in various proportions, but the resulting color is more or less orange. Numerous embedded fibers of tremolite asbestos and/or sussexite give the whole mass a columnar fibrous appearance. Frequently found as a material lining slickensides fractures. 1028
ChlorophaneIs a varietal name of fluorite found at both Franklin and Sterling Hill Mine, which fluoresces greenish-blue or teal green under both short wave and long wave UV light. It also phosphoresces blue under both wavelengths. Chlorophane is thermoluminescent, and will emit these colors if heated. This fluorite is usually brown to sherry-red in daylight, but will fade to a dull brown and eventually to white / clear daylight color on exposure to sunlight or UV light. Heating will destroy the luminescent response, and light exposure will fade the fluorescent response and often change it to the more usual blue fluorite luminescence. 1029
Epidote-(Pb)Was the approved name for Hancockite between 2006 and 2015. In July 2015, the IMA approved a proposal by Olav Revheim and Vandall King to revert the approved name to hancockite.http://www.fomsnj.org/mineral.aspx?minid=254&minName=HancockiteHancockite1013
FerrobustamiteIs the iron analogue of bustamite. It may also contain divalent Mn replacing Fe.  Lathes of white to pink ferrobustamite are sometimes found in specimens of "3rd Find" wollastonite from Franklin, and fluoresce a deep red in SW UV. 1037
Franklin MarbleA band of white marble, extending from south of Sparta, New Jersey, northerly into Orange County, New York. 1021
HyalophaneIs a barium potassium aluminum silicate mineral of the feldspar group. In Franklin it occurs in anhedral crystals and granular aggregates with substantial variation in grain size. It has not been reported to be found at Sterling Hill. Hyalophane is white to pale brown with a vitreous luster varying to somewhat pearly. Some specimens fluoresce a deep red under shortwave UV light. Hyalophane was once on the Franklin Mineral Species List, but was removed in mid-2000’s, after being discredited by the IMA using the 50/50 Rule. (Orthoclase feldspar K(AlSi 3O 8) and celsian Ba(Al 2Si 2O 8) form a solid solution series, which used to include hyalophane as an intermediate member containing both potassium and barium ions.) 1033
IMAThe International Mineralogical Association (IMA) is the world’s largest organization promoting mineralogy. It was founded in 1958 and has 38 national mineralogical societies or groups as members. The Association supports the activities of Commissions and Working Groups involved on certain aspects of mineralogical practice and facilitates interaction among mineralogists by sponsoring and organizing meetings. The IMA Commission on New Minerals, Nomenclature and Classification approves and publishes a list of names and details of new minerals. 1034
JeffersoniteIs a zincian manganoan variety of augite, a clinopyroxene. It is found in large crystals of simple habit, some more than 12 inches long and many doubly terminated. It occurs also in granular and platy masses. The color is dark olive-green to brown and on weathered surfaces is gray to chocolate-brown and black. 1030
LeucaugiteAn outdated synonym for diopside, in use through at least the late1950s. See also zinc schefferite. 1035
Maggot oreHemimorphite crystal clusters that look like fly larva (maggots).http://fomsnj.org/MineralImage.aspx?minIMID=1267&minName=HemimorphiteAn example of maggot ore1004
Red oreThis ore contains pinkish-tan to dark reddish-brown willemite that is colored by franklinite inclusions. 1023
Third FindA Franklin wollastonite occurrence, it occurs in orange-fluorescing elongated grains, or in aggregates of grains, in a matrix of red-fluorescing calcite that also includes smaller grains of cream-fluorescing barite and, rarely, green-fluorescing willemite. A nonfluorescent unidentified amphibole, often as complete crystals, is always present. A locality and date for this occurrence, as well as a description, are given by Baum (1972). What we now call Third-Find wollastonite was found "in the hanging wall at the contact of the ore with the marble to the East, as in the 290 North top slice on the 1050 level, found in 1947”.http://www.fomsnj.org/Fluorescent_Franklin_Mineral.aspx?OFID=108An example of Third Find wollastonite1031
Zinc SchefferiteA local area name for a variety of diopside containing small amounts of zinc. It is light brown in color. At Franklin it often has a platey habit.http://www.fomsnj.org/MineralImage.aspx?minIMID=1328&minName=DiopsideAn example of zinc schefferite1014


Geological Terms
TermDefinition   
50/50 RuleSome minerals are part of a "solid-solution series," with chemical composition and crystal structure that varies from one pure "end-member," through possible intermediate compositions, to another end-member. For example pure scheelite is calcium tungstate, CaWO4, and pure powellite is calcium molybdate, CaMoO4. There could be intermediate minerals with a mix of tungsten and molybdenum, but for simplicity, we say that if the mineral contains more tungsten ions than molybdenum ions – the mineral is termed scheelite. If instead there are more molybdenum than tungsten ions, it is called powellite, with no "50/50" minerals in the middle. 1036
AmphiboleIs a group of closely related, generally dark colored rock forming silicate minerals. 1019
AugenFrom German "eyes", are lenticular eye-shaped mineral grains or mineral aggregates visible in some foliated metamorphic rocks. In a cross section they have the shape of an eye. 1038
BotryoidalA texture or mineral habit where the mineral has a globular external form resembling a bunch of grapes.http://www.fomsnj.org/MineralImage.aspx?minIMID=1268&minName=HemimorphiteBotryoidal mineral example1000
BoxworkIs a mineral-aggregate structure having plates or septa that are often coated with crystals and that intersect at various angles and enclose angular spaces.http://www.fomsnj.org/MineralImage.aspx?minIMID=1349&minName=CalciteAn example of boxwork1032
Calc-silicateA term used to describe rock produced by metasomatic alteration of existing rocks, producing calcium silicate minerals such as diopside and wollastonite. Skarns or tactites are calcium-bearing calc–silicate rocks. 1010
DikeIs a sheet of rock that formed in a fracture in a pre-existing rock body. They can be either magmatic or sedimentary in origin. Magmatic dikes form when magma intrudes into a crack then crystallizes as a sheet intrusion, either cutting across layers of rock or through an unlayered mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack. 1026
ExsolutionIs a process by which an initially homogeneous solid solution separates into at least two different crystalline minerals without the addition or removal of any materials. 1017
FoliatedRefers to repetitive layering in metamorphic rocks that results from segregation of different minerals into roughly parallel layers. Each layer may be as thin as a sheet of paper, or over a meter in thickness. 1015
HomogeneousRefers to the uniformity of composition throughout a rock, texture. For sedimentary rocks, it is the size, shape, and arrangement of the grains. For igneous and metamorphic rocks, texture of a rock or crystals. 1018
LamellaePlural for lamella, is used to refer to collections of fine sheets of material held adjacent to one another. 1016
Metasomatic alterationThe chemical alteration of a rock by hydrothermal and other fluids. It is the replacement of one rock by another of different mineralogical and chemical composition. Some of the minerals which compose the rocks are dissolved, and new mineral formations are deposited in their place.  1011
MylonitizationIs the deformation of a rock by extreme microbrecciation, due to mechanical forces applied in a definite direction, without noteworthy chemical changes to granulated minerals. Characteristically the mylonites produced in this manner have a banded, or streaked appearance, and augen and lenses of the parent rock in a granulated matrix. 1039
PseudomorphIs a mineral that has been chemically altered in some way and is a new mineral which can have a new crystalline structure, but it still retains the shape of the original mineral. These changes occur when the mineral is reduced, oxidized, elements added, or when elements are completely replaced. 1020
SkarnAre calcium-bearing calc–silicate rocks most often formed at the contact zone between intrusions of granitic magma bodies and carbonate sedimentary rocks such as limestone and dolostone. Hot fluids derived from the granitic magma are rich in silica, iron, aluminum, and magnesium. These fluids mix in the contact zone, dissolve calcium-rich carbonate rocks, and convert the host carbonate rock to skarn deposits in a metamorphic process called metasomatism. 1022
Terminated CrystalA single terminated crystal ends in a point on one end of the crystal, whereas a double terminated crystal ends in a point on both sides of the crystal. 1005


Location Terms
TermDefinition   
Balls HillBalls Hill, or Balls Hill Mines, was a string of magnetite mines that was developed on the old Doland Farm in Franklin (then Franklin Furnace), New Jersey. It is located on a now partially removed hill, known locally and noted by Palache (1935) as Balls Hill. Some of the mines were specifically named: Panic, Hill, Mud, Water-Shaft, Wood, Hospital, #3, #4, and Gooseberry Mines; all are on or near Balls Hill. Bayley (1910) reported that the Balls Hill Mines were worked from 1868 to 1880. The Balls Hill Mines closed in February of 1882 (Cook, 1883). (Dunn, 2002, p.51) 1003
Buckwheat DumpAn area created to hold the waste rock from the Buckwheat and Taylor Mines. It is now a mineral-collecting site behind the Franklin Mineral Museum. 1008
EdisonThe Edison Mine was developed in the 1890’s by Thomas Edison, to mine local iron ore deposits on Sparta Mountain, Sussex County, NJ, east of Ogdensburg, NJ. 1027
Franklin FurnaceThis is the old name for the early village where iron furnaces and iron mines were located, near Franklin Pond; the name was changed to Franklin, New Jersey in 1913. 1012
Franklin PondA partially man-made pond located where the early iron-mining in Franklin was centered. It is also known as the Mine Pond, Franklin Lake and Furnace Pond.http://www.fomsnj.org/pdf/Franklin_Pond.pdfFranklin Pond map1024
Hamburg MineWas an early mine on the West limb of the Franklin ore body. It was later part of the Franklin Mine and was also called the Hamburg Road Mine. It had a shaft less than 100 feet deep. 1007
Lang ShaftWas a small shaft that was 100 feet deep, located near the Hamburg Mine, north of the present High Street, Franklin, NJ. It may have been part of the Hamburg Mine, on the West limb of the Franklin ore body. 1006