JVative Crystallized Carbonate of Magnesia. 143 



ijesia in examining the strata exhibited in an excavation now 

 making, under the delusive expectation of finding gold, about 

 three miles from the Quarantine. In descending the shaft, 

 sunk perpendicularly in steatite, magnesite, veins of talc, and 

 green translucent asbestus were observed at depths from six 

 to thirty-five feet. The magnesite was found to embrace veins 

 and cavities containing native carbonate of magnesia, in very 

 white acicular crystals, grouped in minute fibres radiating from 

 the sides, but not always filling the veins and cavities. The 

 crystals were, in some instances, suspended, assuming a sta- 

 lactical form. This carbonate of magnesia dissolves entirely 

 in diluted sulphuric acid, with considerable effervescence and 

 chemical action, producing a bitter compound, from which salts 

 of easy solution are formed by evaporation. The magnesite in 

 which these crystals are found, appears to be composed of car- 

 bonate of magnesia, steatite, and talc, disintegrating readily 

 upon exposure to air and moisture : it effervesces considerably 

 in sulphuric acid, forming a very bitter fluid that soon exhi- 

 bits crystals, indicating that magnesia enters in large propor- 

 tion into its constitution. Magnesite may perhaps be found at 

 this place in quantity sufficient for a successful manufacture of 

 Epsom salts. Small regular hexaedral crystals of mica, were 

 noticed in steatite. Chromate of iron was sparingly diffused 

 through the different minerals raised from various depths. 



A few remarks and facts respecting the geology and minera- 

 logy of Staten-Island, may, perhaps, give some additional 

 interest to the specimens presented. 



Staten-Island (which constitutes Richmond county) is situa- 

 ted about seven miles southwest of the city of New- York, 

 extends from northeast to southwest abaut fifteen miles, in a 

 straight line, with an average width of six. It exhibits a con- 

 siderable diversity of surfoce. The eastern part is composed 

 principally of elevated ground : a mountain chain is observed 

 to take its rise in the vicinity of a narrov/ sound called the 

 Kills, and sweep, in a semicircular form, near the eastern 

 shore; it then ranges southwest, parallel with, and distant 

 from Amboy Bay, about two miles, terminating near the centre 

 of the island, and forming, with the exception of «omo passages, a 



