256 



Third Supplement to Dana's Mineralogy. 



Another of the so-called species is named Glaubapatite. It is described as occur- 

 ring in small tabular crystals, and in druses, forming botryoidal and stalactitic 

 masses, with columnar radiating flattened fibres ; also massive ; color pale yellowish 

 or greenish-brown ; translucent; H.=3'5 ; G.=2-6. Also chocolate-brown to nearly 

 black when massive. Chemical examination afforded, Phosphate of lime 74 00, sul- 

 phate of soda 1510, water 10*30, organic matter, sulphate of lime and chlorid of 

 sodium, a trace =99"40. [From the composition obtained, it can hardly be a chemi- 

 cal compound.] 



Epiglaubite is the name of the third guano product. It occurs " in small aggre- 

 gates or interlaced masses of minute semitransparent crystals of a shining vitreous 

 lustre, which are always implanted upon druses of glaubapatite. H. about 2-5.'* It 

 is stated to be " a largely hydrated phosphate, chiefly of lime, and may also contain 

 magnesia and soda." Soluble in dilute muriatic acid. B.B. fuses easily to a semi- 

 transparent colorless glass tinging the flame green. 



Gypsum [p. 377, and Suppl. n], — Gray's Cave, Sumner Co., Tennessee, affords 

 fine specimens of selenite, snowy gypsum, and " alabaster rosettes." — Safford's Rep., 

 p. 119. 



HARRISITE, C. U. Shepard. — A sulphuret of copper, like copper glance in com- 

 position but cubic in cleavage like the artificial sulphuret. Occurs in imperfectly 

 formed cubes and octahedrons, and also disseminated in seams and massive. Color 

 grayish-black. G.=5'4. Occurs at the Canton Mine, Georgia, with galena in quartz 

 and also crystals of staurotide. A mass of 50 lbs. has been got out. — (Rep. on Can- 

 ton Mine.) 



Heddlite. — See under Conistonite. 



Hematite or Specular Iron [p. 113, and Suppl. n]. — Scacchi has made observa- 

 tions on the hematite of the last eruption of Vesuvius (1855). — [Op. cit. p. 172]. 

 He finds the hematite in crystals and also stalactites and incrustations on the scoria 

 about the small cone. Among them are brilliant crystals, rhombohedrons, of 86° 

 51', and double hexagonal pyramids having the faces inclined to a plane truncating 

 the summit 141° 48'. There are also exceedingly thin scales or laminae which are 

 a lively blood red by transmitted light. 



Besides these, there are octahedral crystals, some with their edges truncated, 

 which are very brilliant, and according to exact measurement the octahedrons are 

 regular or monometric. These octahedrons are intersected, often intricately so, by 

 microscopic laminae which cut through parallel to the octahedral faces, and these 

 laminae consist of hematite or specular iron, being crystalline plates flattened parallel 

 to O (OR), and having on their edges faces of R and other planes of this species. 

 These faces R are so exceedingly minute that M. Scacchi has not been able to as- 

 certain any definite relation in position to those of the octahedron. 



The specular iron of the lava, has often some magnetic qualities. A lamellar variety 

 of the eruption of May, 1855, does not affect the magnetic needle, but manifests 

 sensibly polar magnetism with the magnetoscope. Rhombohedral crystals with 

 truncated summits, from the valley of Cancherone, and bipyramidal crystals from 

 either Somtna or Vesuvius (the locality being uncertain) are sensibly magnetic with 

 the needle, and magnetipolar with the magnetoscope. A group of octahedral crys- 

 tals from the same valley, united on a crust of hematite, is notably magnetic and 

 magnetipolar. Octahedral crystals intersected by lamellae of hematite are strongly 

 magnetic and sensibly magnetipolar. The stalactites of hematite vary much in 

 magnetic qualities. 



Prof. Scacchi questions whether any of the crystals are pseudomorphs, and whether 

 they are magnetite altered to hematite or hematite to magnetite. He says the 

 first is not probable, as hematite is the usual product of sublimation about the 

 volcano; and the second cannot be, as the crystals then should be all rhombohedral. 

 Perhaps, he says, the sesquioxyd of iron is dimorphous : but on this point more evi- 

 dence is required. 



HITCHCOCKITE, C. U. Shepard.—lSo description given, except as follows (Rep. 

 on Canton (Ga.) Mine, 1856) — a white earthy shell, sometimes no thicker than a 

 mere varnish, on marcasite, at a mine affording galena, copper pyrites, blende, mis 

 pickel, automolite. " It is a hydrated phosphate of alumina with oxyd of zinc." 



