1 882.] Mineralogy, 689 



zoisite, idocrase, andalusite, vvitharr 



chlorophyllite, scapolite, pyrrhot 



reddle, lydian stone, hornstone, eh 



be regretted that a careful microscopical examination, especially 



in the case of the silicates, did not precede each analysis. 



On some ill-determined minerals.— -Professor Heddle in this 

 paper again gives new names to species which he himself ac- 

 knowledges are ill-determined and doubtful. 



Plynthite is the name given to a red bole, which falls to pieces 

 in water, and which "probably has resulted from a bed of earth 

 which has been covered and burnt by a trap stream." 



Uigite is a zeolite occurring in radiated, sheafy plates at Uig, 

 Skye, which is but partially described. It is perhaps mesolite. 



Ferrite is an alteration product of pyroxene, which occurs in 

 brown crystals, soft enough to be bruised by the nail. (The name 

 has already been appropriated by Vogelsang to designate a still 

 worse species, the hydrous oxide of iron found in many rocks.) 



Craigtonite. *This name is given to a thin, soft coating of blue- 

 black color adhering to red granite. An analysis was made by 

 putting the minora!, together with the attached granite, in acid 

 and attempting to dissolve the former. The result followed that 

 the granite was attacked, as would be expected from such a method 

 of analysis. The author wisely refrained from reducing the com- 

 position obtained to a formula. The coating is evidently wad. 



hllonitc. "This is an ad interim name given to a pale, dull 

 yellow, somewhat unctuous powder, which I got out of small 

 nests, occurring rarely in perfectly fresh, recently blasted gneiss." 

 The analysis proves that it is a mixture of sand and clav. 



It would be well if Professor Heddle would follow the advice 

 given in the preface to the third appendix to Dana's Mineralogy. 



A peculiar copper ore from New South Wdlcs. — Professor A. 

 Liversidge describes an ore which, though homogeneous in ap- 

 pearance, is probably an tntrmate mixture of quartz and chalcocite. 



On the occurrence of Linarite in Slag.—?. Dudgeon finds well- 

 defined crystals of linarite in the cavities of the slag of an ancient 

 Roman lead smelting place. He supposes that they were formed 

 subsequently to the smelting, during long exposure to the air. 



Some artificial forms of Silica.—}. I'anson and E. A. Parkhurst 

 contribute some interesting results of a course of experiments in 

 the artificial production of agates. They divide banded agates 

 !"to those in which the crvstalline mass 'is outside of the band- 

 m p. and those in which it i's inside, the first showing growth from 

 within outwards, the second from without inwards. They produce 

 both of these forms artificially, by precipitating an alkaline solu- 

 tion of silica by acid. The acid is introduced through a pipette 

 to the bottom of a vessel containing a solution of silica and an 

 alkaline carbonate. As the stream of bubbles arise, silica is de- 

 posited, and in a few minutes a tube is formed, reaching from the 



