68 NEW YORK STATE MUSEUM 
Zo % Zo %o 7% Zo % 
1 High phosphorus, P Fe S) SiO, CaO | MgO | AIO; 
low sulphur en | ee ee | meena | en |e | ee | 
SS | Ss | sf | 
2 Low phosphorus, 0.OI AACR WED AZO. CH I Weis (cell ny pe nell tame tna 
high sulphur to to ROSA AiH Wes mR NMRA SORT RM IMT A Gr he 
—_————— | | | | | — | 
OPAUA Sims een KONO Gis Unrate enue MORIN NCAR 1, 
3 Intermediate to to COML TRA Gk. Oa: ar: 4 WARM DER LY RLS 
OFZ SATEG 757i OMA OAta nee reainrtn | Eee ae EROS Gita ianebaicodt 2 
OSZOLO)| |) BONS) MOL OLA | (TO LST Te LOM nt 725 O87.0 
4 “ Self-fluxing ”’ to to to to to to to 
(rare) a COM vl] KOLO). |] Ode, Ged I) 20d atl) I] Ba MO IP UOSSe) py weea 
The phosphorus is derived from the apatite included in, and 
co-related in origin to the magnetite; some of it is removed during 
magnetic concentration. 
The sulphur is present as pyrite and pyrrhotite, and is likewise of 
the same origin as the magnetite. 
Mines producing high sulphur ore in the past were equipped with 
roasting furnaces which apparently disposed of the sulphur in a 
satisfactory manner. 
Unreplaced remnants of rock universally present in the ores 
(plates 7, 10, 11), consisting of quartz, sericitized and unsericitized 
feldspars, pyroxene and hornblende more or less altered, titanite 
grains, and occasionally mica, sometimes chloritized, will add small 
quantities of silica, potash and soda, alumina, lime and magnesia, 
manganese and titanium to the general composition of the magnetites ; 
but these elements, with the possible exception of silica and 
titanium, have never been reported. With the exception of a few 
complete analyses of the Tilly Foster ore, made by the chemists of 
the 10th Census, no complete analyses of the magnetites of south- 
eastern New York have ever been published. 
THE ORIGIN OF THE MAGNETITE 
All the evidence, both field and petrographic, points to an igneous 
source for the magnetite. This is entirely in accord with the ideas 
of those geologists who have studied similar deposits in the 
Adirondack region and in the adjacent Highlands area in New 
Jersey, during the past 10 or 12 years. The writer, however, has 
