272 Sir C. L. Gieseck's Account of a Mineralogical [April, 



to the Serpentine Antico of Italy, is mixed with steatite, fine 

 granular limestone and stripes of asbestus, and occurs in blocks 

 sometimes of the length of 12 and 13 feet, and three or four tons 

 in weight. It is impossible to describe the immense varieties of 

 delineations and shades and colours of this beautiful stone, 

 which attract the eye of the beholder; the serpent-like delinea- 

 tions of some of them must excite particular admiration. Others 

 are coloured in spiral forms, others are dotted and spotted with 

 different shades of green, grey, and yellow. Solid masses of an 

 enormous size may be raised. Mr. Martin has already quarried 

 out an immense quantity, part of which is cut in slabs for tables, 

 and which are ready for sale. He has also made a road from 

 the quarry to the port, a distance of six miles, but it would 

 require a railroad for large blocks. Higher up towards the north- 

 west of the Twelve Pins, there occurs a kind of serpentine which 

 contains but very little of the grey and white granular limestone. 

 The limestone seems here rather to form small beds in the 

 serpentine. 1 found along the river large blocks of granite with 

 imbedded and nine-sided prisms of tourmaline of a pitch-black 

 colour, similar to that of Killiney. The granite of the country 

 is fine and coarse granular, very durable; and abounds in felspar 

 of a flesh-red and reddish-brown colour; beds of felspar occur in 

 it. Another quarry of serpentine, which was worked formerly 

 by Mr. D'Arcy, of Clifden, is now in the possession of the 

 Hibernian Mining Company. On another day I went by a boat 

 to the black marble quarry four miles from Galvvay, which is 

 worked bjf Mr. Ireland, and to another at Merlin Park, the 

 property of Mr. Blacke : the latter is of the most beautiful jet 

 black colour, and very transparent ; the former is rather of a 

 slaty structure, and on that account easier worked. It contains 

 numerous petrefactions, particularly of gryphites, and is some- 

 times intersected by small veins of fluor. As the quarry is 

 situated close to the shore, the marble is carried in great quan- 

 tities to the neighbouring country, and also to London. 



County of Mayo. 



I entered the County Mayo on the road leading through the 

 little town or Cong, a place remarkable on account of its subter- 

 raneous springs and extensive caves, through which rapid 

 streams run in different directions. The rocks consist of fine 

 granular slaty sandstone, in which there are found in nests most 

 beautiful specimens of perfectly transparent glass-white and 

 yellowish-white calcareous spar of a rhomboidal shape, not 

 inferior to those known by the name of Icelandic double refract- 

 ing spar. The walls and the roofs of the caves are covered and 

 decorated with calcareous stalactites of greyish-white and 

 yellowish-grey colours, and of different shapes. In the river 

 close to a mill there is a whirlpool, and near to the church fine 



