502 



Scientific Geology. 



prolific locality, — that in Hatfield, — occurs in sienite, and has been 

 described. A considerable part of the matrix of galena, blende, and 

 copper pyrites, at the Southampton mine, consists of this mineral. 

 The most southerly vein of lead ore in Leverett, also, abounds in it, 

 as the gangue of the galena. And both the metallic veins in that 

 place are in granite. The baryta occurs generally in foliated masses : 

 sometimes in tabular crystals. The folia are sometimes curved ; and 

 sometimes, as in Leverett, the specimens are coarsely granular. The 

 color is uniformly white. 



Carbonate of lime is rare in granite : but in the vein of metallic 

 ores above spoken of at Southampton, we find it in distinct crystals; 

 sometimes of a delicate straw color. I have observed there a dodec- 

 aedeon composed of two six sided pyramids : a short six sided prism 

 acuminated by three faces : also the same with all the solid angles 

 of the prism truncated, producing a trapezoedron. This mineral 

 more frequently is laminated. 



The situation of the argentine in West Hampton, partly in the mi- 

 ca slate and partly in the granite, renders it proper to speak of it as 

 belonging to either rock : but under micaceous limestone I have given 

 a full description of its geological position, and its mineralogical 

 characters correspond so well with those that are given in the books, 

 that nothing more need be added. The locality cannot for a consid- 

 erable time, if ever, be exhausted ; unless it should be visited by some 

 of those insatiable collectors, who carry away specimens by the ton. 

 (Nos. 1490, 1491.) 



This same mineral has been found at the Southampton lead mine. 



At the most northerly vein of galena and pryritous copper in Lev- 

 erett, I have found a few specimens of crystalized brown spar. 



In Billerica and Stow, phosphate of lime has been found by Profes- 

 sor Webster in very coarse granite : Also by Mr- C. T. Jackson, in 

 the same rock in Lancaster, in connexion with spodumene. 



At the Southampton lead mine, green and purple fluate of lime has 

 been found, but not in large quantities : though should this mine ever 

 be wrought extensively, there can be little doubt that abundance of it 

 will be brought to light. 



At the same place we meet with crystalized limpid quartz in great 

 abundance. Sometimes the crystals are penetrated throughout by a yel- 

 low colouring matter, so as to form genuine yellow quartz. Radiated 

 quartz forms the greater part of the gangue of the lead and copper 

 ores, in the several veins of these metals that have been described as 

 existing in Hampshire county, in the first part of this report. In 



