I forward you a few mineral specimens characteristic of Staten-Island, including native carbonate of magnesia, in acicular crystals. I discovered this new form and locality of magnesia 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 stalactical 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 carbonate 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 exhibits crystals, indicating that magnesia enters in large proportion 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 mineralogy of Staten-Island, may, perhaps, give some additional interest to the specimens presented.