IRON. 



401 



Dr. Thomson remarks, that the reason of the difference in the results of Vauquelin, Lau- 

 gier, Klaproth, Seybert and Berthier, is that they did not employ pure specimens. He denies 

 that silica is essential to the mineral, as has been asserted by Berthier and others. 



Geological Situation. This mineral occurs in beds, veins and detached grains or crystals, 

 in serpentine, porphyry and trap rocks. In this State, it is found only in small quantities in 

 the beds of serpentine, and of the allied minerals. 



Uses. Chrome-iron ore is employed in the manufacture of the chromates, some of which 

 are highly esteemed and largely used as paints. 



LOCALITIES. 



Putnam County. Crystals of chrome-iron ore are occasionally met with in the serpentine 

 and magnesian carbonate of lime at Hustis' farm in Phillipstown. A crystal has been obtained 

 here, with the base a quarter of an inch in diameter. It resembles black spinelle, but its 

 powder is attracted by the magnet, and its blowpipe characters agree with those just noticed. 

 Minute grains or crystals of the same mineral have also been found in the vicinity of 

 Carmel, in this county. 



Orange County. Minute octahedrons of chrome ore are found in a talcy mineral accom- 

 panying a bed of magnetic iron ore, at the Wilks mine in the town of Monroe. 



Richmond County. Octahedral crystals of this mineral have long 

 been credited to the serpentine at the Quarantine and elsewhere in this 

 county. It is probable that they have sometimes been nothing more 

 than magnetic iron ore. 



Westchester County. The serpentine near Rye and New-Ro- 

 chelle, contains black metallic grains, which are supposed to be chrome 

 iron ore. 



Fig. 476 represents a modified octahedron of this mineral, found 

 at Hoboken in New- Jersey {Shepard.) 



Fig. 476. 



VIVIANITE. 



Fer Phosphate. Haiiy. — Phosphate of Iron. Ckaveland and Phillips, — Vivianite. Tkomson, and Shepard. — 

 Prismatic Blue Iron. Jameson. — Dichromatisches Euklas-Haloid. Mohs. 



Fig. 477. 



MiN. — Part II. 



Description. Colour varying from pale green to indigo- 

 blue. Streak bluish white, but on exposure changing to in- 

 digo blue. It occurs regularly crystallized ; also massive, 

 disseminated, and in thin coats. Primary form a right oblique 

 angled prism. Fig. 477. M on T 125° 18'. Cleavage per- 

 fect parallel to P. Lustre pearly, inclining to metallic, on P ; 

 on the other faces, vitreous. Varies from transparent to 

 opaque. Hardness from 1.5 to 2.0. Specific gravity 2.66. 

 51 



