246 Js^ullalPs Geological and jMincralogical Remarks. 



ted often towards the base of the calcareous beds, and conti- 

 guous to foreign infiltrations or veins. A nii!e south of 

 Franklin furnace it is also seen imbedded in a gray massive 

 augite, accompanied by mica and fiuate of lime: the blue 

 iluate here also forms slender illinitions in the marble. 

 Near to this spot tremolite and small imbedded crystals of 

 white augite ? and of actynolite occur: short crystals of 

 augite. almost black, like those of volcanic rocks are also 

 now and then visible ; a beautiful apple green felspar as in- 

 dicated by the goniometer, occurs imbedded in the crystal- 

 line carbonate of lime, accompanied by perfect crystals 

 of mica, and hexagonal plates of plumbago-, this felspar is 

 unusuall}' soft, and almost as fusible as hornblende. A very 

 brilliant pale green hornblende, passing into actynolite is 

 often found massive and in implicated crystalline confused 

 crusts over the surface of the calcareous beds. 



This hornblende considerably resembles the supposed 

 hypersthene of Delaware, recently analyzed by Mr. Sey- 

 bert, who considered it as hornblende; it however gives 

 the goniometrical measurement of hornblende, while the 

 Delaware mineral, according to the observation of Dr. Tor- 

 rey, gives by cleavage, a prism which is nearly rectangular, 

 or with angles of 88° and 91°. 



It forms, therefore, a new species, which w^e propose to 

 name Maclurite, in honour of him w};o h?s done so much 

 for American geology, and natural science in general. 



According to Mr. Seybert, it contains in the 100 parts: 

 water 1,266; silex 52,166; deutoxide of iron 10,733; 

 manganese a trace ; alumine 4 ; lime 20 ; magnesia 1 1,333. 

 From which an obvious affinity to augite presents itself, as 

 it actually differs less in chemical composition from augite, 

 than the two analyses of augite, given in Cleaveland, differ 

 from each other; it fuses also with difficulty; but as the 

 crystalline structure is essentially distinct, it must necessa- 

 rily be considered as a species destitute of every affinity 

 with hornblende, from which at the same time it is scarcely 

 distinguishable, except by the cleavage. In degree of fu- 

 sibility, in its hardness, colour, laminar texture, metallic 

 brilliancy, and specific gravity, it is scarcely to be distin- 

 guished from the green stone. 



In another neighbouring locality, enormous green crystals 

 of augite are found, some at least an inch and a half in diam- 

 eter, presenting hexaedral or octahedral prisms, with almost 

 equal faces, and terminated by obiique tetrahedral pyramids. 



