Geology, <^c. of the Connecticut. 213 



14. Sulphate of Alumine and Potash. (Alum.) In Ley- 

 den, efflorescing on bastard argillite. Also in Conway, on 

 mica slate. 



15. Common Quartz. 



1. Limpid Quartz. At Grafton in Vermont, remarkably 

 pure. (Hall.) Also at Plamfield. (/. Porter.) Also in the 

 veins of lead, &;c. at Southampton and Leverett, and the 

 copper veins in Greenfield, in six-sided prisms. At the lat- 

 ter place it occurs with both the terminations perfect. Also 

 in veins in sienitic granite, at Northampton. Also in ge- 

 odes in greenstone at New-Haven, Berlin and Deerfield. 

 Also in veins and geodes from one to ten inches diameter, 

 in mica slate in Conway. The crystals are of every size 

 from one tenth of an inch to two inches diameter, and occur 

 in vast quantities. In the same town fragments of crystals 

 occur, as transparent as the quartz from Madagascar, 



2. Smoky Quartz. At Torrington and Cornwall, (Brace.) 

 Also at Plainfield and Brattleborough f amorphous. 



3. Yellozo Quartz. In crystals at the Southampton lead 

 mine; of a honey yellow, resembling the Siberian topaz. 

 The coloring matter appears to penetrate the crystals. Al- 

 so ia small quantities at the lead mine in Leverett. 



4. Rose-Red Quartz. At Southbury, very abundant. (Sil- 

 liman.) Also at Chatham and East-Haddam. (T.D. Porter.) 

 Also at Deerfield ; a single specimen in alluvial soil. 



5. Irised Quartz. At Plainfield. (J. Porter.) Also at 

 Leyden, in mica slate. 



6. Milky Quartz. At Litchfield. (Brace.) Also at Cum- 

 mington and Plainfield. (J. Porter.) The specimens that 

 I have seen of this variety (and they are scattered abundant- 

 ly over the mica slate region west of Connecticut river,) are 

 rather poorly characterized, seeming to be intermediate be- 

 tween limpid and milky quartz. 



