Dr. Aquila Smith on Irish Tin Ore. 135 



scribed in the catalogue of the minerals in Trinity College 

 Museum, drawn up in 1807 by the late Rev. Walter Stephens, 

 no specimen of Irish tin-stone is mentioned ; and even at a 

 later period, in 1818, when my respected friend, Dr. Whitley 

 Stokes, published his catalogue, Irish tin-stone is not to be 

 found in the list. 



These circumstances would almost induce us to suspect 

 that some other substance must have been mistaken for tin- 

 stone by the directors of the works at the gold mine. 



The next notice of this metal being found in Ireland is in 

 the catalogue of Irish minerals in the museum of the Royal 

 Dublin Society, published in 1832 by the late Sir Charles 

 Giesecke. No. 213 is thus described: "tin-stone of a hair- 

 brown colour, accompanies frequently, in small grains, the 

 native gold found in streams at Croaghan mountain, county 

 Wicklow." 



Ever since I have turned my attention to mineralogy, I have 

 anxiously sought for a specimen of Irish tin ore, in our public 

 museums, as well as in several private collections of Irish 

 minerals, but was unsuccessful in discovering any such spe- 

 cimen. 



About six weeks ago I received, through my friend Mr. 

 Robert Mallet, a small paper of washed sand from the gold 

 works at present carrying on at Croaghan mountain, under 

 the superintendence of Mr. Suter, who sent me the sand for 

 the purpose of having it examined. 



I found in it the following minerals : — 



1. Several minute particles of native gold. 



2. Magnetic iron ore consisting chiefly of very minute 

 and brilliant octahedral crystals, readily separated by the 

 magnet. 



3. Fine-grained specula iron ore, giving a red streak when 

 scratched with a knife, and becoming magnetic when heated. 



4. Numerous minute garnets of a pale red colour, some of 

 them exhibiting the planes of a rhombic dodecahedron, and 

 fusing readily without intumescence into a brilliant black 

 globule. 



5. Many fragments of an earthy looking mineral, some of 

 them presenting crystalline planes, abraded by friction ; the 

 fracture was shining, and the hardness about = 6*0 or that 

 of felspar. Not being certain as to what this mineral was, I 

 proceeded to examine it more particularly. In the forceps 

 when heated it became yellow, and in a strong heat deposited 

 a white sublimate on the points of the forceps, but it did not 

 fuse. I then tried it on charcoal, but from the difficulty of 

 keeping so small an assay steadily fixed under the flame, the 



