?! 



400 Domestic. 



This mineral is easily cleaved in one direction, exhibitmg 

 brilliant folia, with a sli^^ht pearly lustre. It is hard enough 

 to scratch glass feebly. By the heat of a candle it distinct- 

 ly exfoliates, and before the blowpipe, intumesces conside- 

 rably. It does not form a jelly with acids.* 



5. Siliceoiis Oxyd of Zinc. — On examining a few weeks 

 since, some specimens of mineral brought by Mr. NuUall, 

 from Franklin furnace in N. Jersey, I found among them 

 the siliceous oxyd of zinc. It occurs in irregular masses, 

 from an inch to three inches in diameter, disseminated in 

 Franklinlte. It is generally more or less mixed with the 

 red oxyd of zinc. Its appearance when pure much resem- 

 bles granular quartz. In fine powder it dissolves immedi- 

 ately in nitric acid, and the solution gelatinizes strongly. 

 Since 1 examined this mineral, Dr. LangstafF informs me 

 that he discovered it many years ago in the same place 

 where it was found by Mr. NuttalL 



Mr. Geo. Boyd, a young and promising mineralogist, of 

 this city, has just returned from a visit to Patterson and the 

 neighbourhood of Sparta, and has brought with him a good 

 collection of the minerals of these interesting localities, most 

 of which are described in Mr. NuttalFs memoir. At the 

 former place he examined the well where the Datholite is 

 found, h occurs in large geodes in trap, about twenty feet 

 below the surface of the earth. Some of the crystals which 

 he found were an inch in length. But very small quantities 

 of Datholite have yet been found except at this place. 



6. Franklinitc. — A fragment of this mineral, two Inches 

 in diameter, with four very perfect sides, was found by Mr. 

 Boyd, near Franklin Furnace. He also found small crys- 

 tals of the same mineral, exceedingly perfect, and with a 

 lustre litde inferior to that of spinelL% They were octabe- 

 jdral, with the common base and lateral edges truncated. 

 On examining these crystals, which were more perfect than 

 those I received for Mr. Nuttall^ I make the angle of the 

 inclination of the pyramids 109^, which is almost exactly 

 that of spinelle. 



* I have beeo particular In describing this mineral, ys the Stilbite has 

 been recenUy divided into ieveral specie?, and it i:* probable tliis constitutes 

 one <rf them. J.T- 



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