Review of Dana's Mineralogy. 383 



year, suggests the union of Sillimanite, Kyanite,* and Andalusite, 



under the general formula Al 3 Si 2 . There are strong reasons 

 for believing that silicate of alumina is a dimorphous substance, 

 and on this supposition we may consider Sillimanite one of its 

 forms. Mineralogically Sillimanite is certainly distinct. 



Iolite. — We have the following analyses of Iolite from Had- 

 dam, Ct. and Unity, in New Hampshire, by Dr. Jackson, (p. 406.) 



10005 99-49 



Ilmenite. — " The Washingtonite of Shepard, a variety of Ilmenite 

 has been analyzed by J. S. Kendall in Dr. C. T. Jackson's laboratory 

 and found to contain titanic acid 25-28, peroxyd of iron 51-84, pro 

 toxyd of iron 22-86=99-98. It appears therefore to be nearly identi 

 cal in composition with the hystatic iron ore of Breithaupt, or the Hys 

 tatite variety of this species." (p. 527.) 



If we were to form our estimate of the progress of American 

 mineralogy by taking into view the number of exploded species 

 of American minerals only, we should be forced to conclude that 

 such progress was of rather an equivocal nature. But we must 

 bear in mind that the science is burthened with hundreds of 

 synonyms of European minerals which still hold a place in the 

 index of the present work, while too many of the bad American 

 species have been proposed by foreign authors. There can be 

 no objection to giving the following alphabetical list of Ameri- 

 can species which have been proposed and subsequently aban- 

 doned. The list is made out from our own opinions, and it is too 

 much to expect that it will meet in all cases the views of authors. 



* The Kyanite from Chesterfield in Massachusetts, has been recently analyzed 

 by one of my pupils, (Mr. C. H. Rockwell of Norwich.) The specimen was 

 finely crystallized, transparent, and azure colored : it yielded 



Silica, - 4274 



Alumina, ..... 5790 



Iron, ----.- trace. 



100 64 

 This analysis adds farther confirmation to the views expressed in the text. — 

 B. S., Jr. 



