60 ECONOMICAL MINERALOGY. 



spathic rocks, but the precise nature of the changes which lake place has not yet been ascer- 

 tained. 



As for feldspar, used in glazing, and also in the body of the finer kinds of potter)', we have 

 several localities in Orange county, in Warren county near Caldwell, and also in the counties 

 of Jefferson and St. Lawrence ; while quartz, of a good quality and in sufficient abundance 

 for the same purpose, is found in Orange, Columbia and other cdunties. 



Those who are at all acquainted with the history of the arts, both in this and in other coun- 

 tries, must be aware that their progress has oftentimes been extremely slow ; and it will not 

 be surprising if the manufacture in question, although now of so little value to us, should be- 

 come an extensive and important one. Previously to about the year 1760, England depended 

 wholly upon other countries for the finer kinds of pottery, the Enghsh ware being generally 

 of an inferior quahty ; but in a few years after the investigations and consequent improvements 

 of Mr. Wedgewood, the current of importation of even the finer earthen wares was changed 

 in that country to exportation, and their manufacture has at length become of such vast extent 

 that it is not easy to calculate its value. So it has been with many of the arts now success- 

 fully prosecuted in our own country. A great number of articles, for which we were but a 

 few years since entirely dependent on foreign nations, are now manufactured by our mechanics 

 and in our own workshops. 



. STONE PAINTS, OCHRES, &c. 



In my notice of our iron ores, it has been remarked that many of the varieties of the specular 

 oxide of iron, and of the limonite, in different parts of the State, are employed as paints. 

 They answer well for this purpose, not only in consequence of the fine colour which they often 

 possess, but of the manner in which they unite with oils. 



There are some other minerals which may be noticed here, in consequence of the use which 

 has been made of them as paints. I refer now to the sulphate of barytes and the carbonate 

 of strontian. The former of these. minerals, which can easily be distinguished from marble 

 which it sometimes resembles, by its greater specific gravity, is now used quite extensively as 

 a substitute for white lead. Of this mineral we have several localities, I5ut it has not hereto- 

 fore been found here, in so great abundance as in some of the neighboring States. At Pillar 

 Point in Jefferson county, it has been obtained in large blocks, and is compact, variously co- 

 loured, and susceptible of polish. It is also found in St. Lawrence, Herkimer, Greene and 

 Schoharie counties. 



The carbonate of strontian, of which a stratum occurs at Schoharie, might be employed for 

 a similar purpose ; as its specific gravity, although not quite so high as the sulphate of barytes, 

 is higher than that of moet other earthy minerals. It is, moreover, of a white colour, emd is 

 easily reduced to powder. 



