LIME. 



247 



at Bergen hill. Crystals of the primary form (Fig. 119), and very complex secondary ones, 

 have been found here in considerable abundance. They sometimes very nearly resemble 

 those of calcareous spar, occurring at the same locality, and the latter have probably often 

 been mistaken for them. The different action of acids forms a good distinctive character. 

 Datholite is also found in the trap at Paterson, and in other parts of New-Jersey. 



Westchester County. Small crystals, presenting the primary form slightly modified, 

 have been found in veins of calcareous spar, with analcime and iron pyrites, in the gneiss near 

 Yonkers. They are, however, of rare occurrence. 



According to Prof. Shepard, the variety Humboltite occurs in trap at Middlefield and Ham- 

 den, Connecticut. 



Fig. 122. 



PHARMACOLITE. 



[From the Greek (papjiaxos, in allusion to its containing poison.] 



Chaux Arseniatee. flffiiiy. — Arseniate of Lime. Cleaveland. — Bisesquihydrous Arseniateof Lime. T^rmson. — 

 Hemiprismatic Gypsum-Haloide. Haidinger. — Hemiprismatisches Euklas-Haloid. Mohs. — Pharmacolite. 

 Beudant, Shepard and Dana, 



Description. Colour white or greyish white. It occurs in minute fibrous or acicular 

 crystals, which are usually aggregated into botryoidal or globular masses ; more rarely in 

 distinct crystals. The primary form is aright obhque angled prism (Fig. 121). Fig. 122 

 Fig. 121. represents one of the secondary forms : 



/ on/ 117° 24'; o to the edge between 

 / and / 83° 14'. Cleavage parallel to T, 

 highly perfect, and easily obtained. Frac 

 ture uneven. Lustre glimmering or silky. 

 Transparent or translucent. Hardness 2 . 

 to 2.5. Specific gravity 2.73. Before 

 the blowpipe, it is almost entirely volatilized with a dense white arsenical vapour. In nitric 

 acid, it dissolves readily without effervescence. 



Composition. Lime 25.00, arsenic acid 50 . 54, water 24.46 {Klaproth). 



In regard to this mineral, it may be remarked, that most of the above characters were 

 obtained by Haidinger from a specimen which he supposed to come nearer to pharmacolite than 

 to any other species. It was received by him under the name of selenite. His remarks are as 

 follows : " It is very likely not an entirely new species, but a variety of pharmacolite, now 

 observed for the first time in crystals large enough to admit of measurement, and to allow the 

 characters derived from hardness and specific gravity to be ascertained to a considerable 

 degree of exactness. The pharmacolite itself cannot be called a species which we know, 

 since the whole of our information respecting its natural-historical properties is confined to 

 its occurring in exceedingly delicate white capillary crystals, aggregated in globules, the 

 specific gravity of which is 2.64. The lower specific gravity might perhaps be accounted 



