1886.] NEW YORK ACADEMY OF SCIENCES. 239- 



This Staten Island rock is occasionally varied by a slaty struc- 

 ture (talcose slate), of a general reddish-brown tint, sometimes 

 showing a variegated aspect, like rare woods for ornamental pur- 

 poses. This slaty and schistose structure readily passes into a 

 fibrous condition, affording specimens of asbestos, some of which 

 is tough and wood-like, others flexible as flax. The finest va- 

 riety, known as amianthus, is as soft as silk. 



Some of the more interesting minerals here noticeable are 

 marmolite (a foliated serpentine), kerolite, and gurhofite, more 

 solid and compact, and of a creamy-white color, resembling por- 

 celain. The marmolite is often found twisted and twirled in a 

 curious manner. 



Among the vein minerals are talc, dolomite, and aragonite, the 

 first-named in laminated masses across the course of the vein. 

 Its colors are Avhite, yellow, and light-green. These tints are 

 often S])0tted by impurities. Talc is often found in a pulveru- 

 lent state at the various iron mines. In fineness it surpasses 

 flour; the color is a delicate brown. 



The limonite beds of the island may next attract the collector 

 of minerals. These deposits are some half-dozen in number, 

 and have in years past proved of commercial value. At present, 

 the supplies are not as plentiful as heretofore. 



The limonite is found in mammillary, botryoidal, and stalacti- 

 tic forms with higlily lustrous surfaces. Tlie most interesting 

 specimens are those with velvet-like surfaces of a beautiful brown 

 color in varying shades. 



The most extensive of the mines on the island is that known 

 as the "Eichmond,'^ near Port Eichmond. In addition to tlie 

 solid ore here obtained, there existed, years since, extensive de- 

 posits of the yellow and red oxides of iron several feet in depth. 

 This earth has been used in the manufacture of paint, but the 

 deposit is nearly exhausted. 



Considerable ore has been taken from deposits on Todt Hill,, 

 also from a local itv near New Dorp, and one or more points near 

 Clifton. 



The quartz rock at the various mines is of a highly cellular 

 character, the cavities lined with crystals. The presence of the 

 various iron oxides affords a great varietyof tints, the chief of 

 which, the green variety, gives Staten Island a conspicuous place 

 in mineral catalogues. Other colors are yellow, brown, cinna- 

 mon, and black. The Eichmond mine has afforded handsome 

 specimens of a colorless variety, also of a delicate lavender tint. 

 Prismatic planes are quite unusual among the crystal forms. 



This is otherwise with the green quartz at the Todt Hill and 

 Clifton localities, where the crystals are complete, with double- 



