The Ore Deposits

Average composition of the ore

The average mineral and chemical composition of the ore of the Franklin district, as established by many hundred mill and assay tests, is approximately as follows:

Average mineral and chemical
composition of the ore of the Franklin district

Mineral Composition	percent
franklinite	43
zincite	1
willemite	26
other silicates, such as garnet and rhodonite	5
calcite	25
	100

Chemical Composition	percent
ZnO	31
FeO	25
MnO	10
SiO₂	9
CaCO₃	25
	100

The data in the first column were kindly supplied by the New Jersey Zinc Company, with permission to publish them. The chemical composition was computed from them and is not exact, as some of the iron and manganese should be stated as sesquioxide.

In contrast to the rather simple mineral composition of the ore bodies as a whole are the number and variety of the minerals they contain in very minor amount. Of the more than 140 minerals found in the district, at least 120 are found in the zinc-ore deposits, and nearly 100 are found only in those deposits. (See list, below.) In the following sections the association of the minerals in groups according to their geologic occurrence is described, with special reference to the further grouping of the minerals in the zinc ores according to their genetic relations. In order to concentrate attention on the problem of the origin of the zinc ores, the minor mineral associations will be described first.

Alphabetic list of the minerals of the Franklin district, showing their geologic occurrence
(Occurrence in the zinc ores is indicated by A, in the pegmatite bodies by B, in the magnetite ores by C, in the Franklin limestone D, in the Kittatinny limestone by E. Minerals seen only as essential constituents of the rocks of the district are not included)

Actinolite – A, B, C, D.

Albite – A, D, E.

Allactite – A.

Allanite – B, C.

Andradite – A, B, C, D.

Anglesite A.

Anhydrite – A.

Anorthite – D.

Apatite – A, B, C, D

Apophyllite – A.

Aragonite – A.

Arseniosiderite – A.

Arsenopyrite – A, C, D, E.

Aurichalcite – A.

Azurite – A.

Barite – A.

Barylite – A.

Barysilite – A.

Bementite – A.

Beryllium vesuvianite – A.

Bornite – A.

Bustamite – A.

Cahnite – A.

Calamine – A.

Calciothomsonite – A.

Calcite – A, D, E.

Calcium larsenite – A.

Celestite – A.

Cerusite – B.

Chalcocite – A.

Chalcophanite – A.

Chalcopyrite – A, B, D.

Chloanthite – A.

Chlorite – A.

Chlorophoenicite – A.

Chondrodite – D.

Clinohedrite – A.

Copper – A.

Corundum – D.

Crocidolite – A.

Cuprite – A.

Cuspidine – A.

Cyprine – A.

Datolite– A.

Desaulesite – A.

Descloizite – A.

Diopside – A.

Dolomite – A, D.

Edenite – D.

Epidote – A, B, C.

Ferroaxinite – C.

Ferroschallerite – A.

Fluoborite – A.

Fluorite – A, B, D, E.

Fowlerite – A, B.

Franklinite – A.

Friedelite – A.

Gageite – A.

Gahnite – A, D.

Galena – A, B, D, E.

Ganophyllite – A.

Glaucochroite – A.

Goethite – A.

Graphite – D.

Greenockite – A.

Gypsum – A.

Halloysite – A.

Hancockite – A.

Hardystonite – A.

Hastingsite – A.

Hedyphane – A.

Hematite – A, D.

Hetaerolite – A.

Heulandite – A.

Hodgkinsonite – A, D.

Holdenite – A.

Hyalophane – A.

Hydrohetaerolite – A.

Hydrozincite – A.

Ilmenite – D.

Jeffersonite – A, B.

Kentrolite – A.

Larsenite – A.

Lead – A.

Leucaugite – A, C, D.

Leucophoenicite – A.

Limonite – A.

Lollingite – A.

Loseyite – A.

Magnesium chlorophoenicite – A.

Magnetite – A, B, C, D.

Malachite – A.

Manganbrucite – A.

Manganite – A.

Manganoaxinite – A.

Manganophyllite – A, C.

Manganosite – A.

Marcasite – D.

Margarosanite – A.

Mcgovernite – A.

Microcline – B, C.

Millerite – A.

Molybdenite – C, D.

Mooreite – A.

Muscovite – B, D.

Nasonite – A.

Neotocite – A.

Niccolite – A.

Norbergite – D.

Pargasite – A.

Pectolite – A.

Phlogopite – C, D.

Prehnite – A.

Psilomelane – A.

Pyrite – A, C, D.

Pyrochroite – A.

Pyrrhotite – D, E.

Quartz – A, B, D, E.

Rhodochrosite – A.

Roeblingite – A.

Roepperite – A, D.

Rutile – C, D.

Scapolite – C, D.

Schallerite – A.

Schefferite – A.

Serpentine – A.

Siderite – A.

Silver – A.

Smithsonite – A.

Sphalerite – A, B, E.

Spinel – B, C, D.

Stilbite – A, B.

Sussexite – A.

Svabite – A.

Talc – A, D.

Tennantite – A.

Tephroite – A.

Thorite – B.

Titanite – B, C, D.

Tourmaline – D.

Tremolite – A, D.

Willemite – A.

Xonotlite – A.

Zincite – A.

Zinc cummingtonite – A.

Zinc schefferite – A.

Zircon – B, C.

Zoisite – B.


	Website © by Herb Yeates 1997-2001.
	This page created: January 12, 2001 6:58 PM