_Sulphat of Barytes, with Coal, &c._--Sulphat of barytes exists abundantly in Southington, on what is called the Clark Farm. With quartz, carbonate of lime, &c. it forms the gangue of a metallic vein, containing galena, or sulphuret of lead, copper pyrites, &c. The sulphat of barytes is more or less crystallized, and principally in the form that is called the coxcomb spar. The same vein, although it is in the side of a mountain, several hundred feet above the flat country adjacent, and two or three miles from the coal strata above mentioned, contains numerous spots and patches of coal, very much resembling that at Suffield. It is of a most brilliant black, and contrasted with the white, stony matrix, (principally quartz and sulphat of barytes) in which it is enveloped, it forms elegant specimens. _Scintillating Limestone._--In Vermont, a singular scintillating limestone is found, of which an account is given in the following extract of a letter from Mr. George Chase, dated Randolph, February 19, 1818. "The object of the present letter is to acquaint you with a circumstance relating to the limestone that abounds in this primitive country, which to me is inexplicable. This carbonate of lime is of a pale sky-blue colour; effervesces strongly with nitric acid; and, by burning, produces lime, so that there is no question as to the identity of the mineral. But it likewise gives forth sparks with steel:--this I concluded, at first, to be an accidental circumstance; but every specimen that I have tried, from various quarters of the country, uniformly gives fire with steel. The limestone is found in layers, in blocks, and masses, disseminated among the clay-slate that covers the greatest part of the townships in this vicinity. When first taken from the earth, and exposed to the air, it is covered with an incrustation of a dark reddish-brown colour, that crumbles easily between the fingers, and is generally from one inch to a foot in thickness. This incrustation, however, hardens on a long exposure to the air. This led me to think that the incrustation was owing to the decomposition of the limestone, which was produced by the sulphuret of iron, intimately disseminated through the rock, which would also explain the singular circumstance of its striking fire. But on dissolving a small quantity of the mineral in nitric acid, and adding a drop or two of the decoction of gallnut, no discolouring of the liquor was produced." _Limpid Quartz._--West Canada Creek, a northern branch of the Mohawk, affords, in its sands, small crystals of quartz, limpid, and terminated at both ends by pyramids of six sides; we are indebted for specimens to Professor Fisher.