132 Mr. Vanuxem's Description of a Lamellar Pyroxene. 



The lamellar pyroxene is found about three miles above 

 West Point, on the western side of the river, and near to the 

 water's edge. It is associated with hyaline quartz, black and 

 bronze coloured mica, and feldspar ; the latter but in small 

 quantity. These minerals form an aggregate of limited ex- 

 tent, which is a dependant of our sienitic formation, which 

 there covers the whole of the country included under the 

 name of the Highlands of the North River. 



The lamellar pyroxene of West Point is identical in all its 

 characters, both external and chemical, with that mineral of 

 Brandywine (Delaware State) which was first considered to 

 be hypersthene, from similarity of colour, and from its pre- 

 senting the same lamellar structure in one direction, as exhi- 

 bited by the Labrador mineral ; the same which subsequently 

 was analysed and described as an amphibole by Mr. H. Sey- 

 bert; whose account was published in the Journal of the Aca- 

 demy, vol. ii. p. 139; and to which, more recently, Mr. Nuttall 

 and Dr. Torrey have proposed to give the name of Maclureite, 

 supposing it to be a new mineral. (See Silliman's Journal, 

 vol. v. p. 246.) 



Those to whom the characters of these minerals are fami- 

 liar, will have much less difficulty in identifying the mineral 

 in question with pyroxene, than with either of the other two 

 minerals, with which it has been confounded ; and further, 

 will have no reason for believing that it should not be classed 

 with pyroxene, in the present state of our mineral ogical know- 

 ledge: this being admitted, its new name of Maclureite be- 

 comes superfluous and objectionable. To American minera- 

 logists this circumstance cannot but be a subject of regret ; 

 for it is not the only attempt* that has been made to confer 

 this merited tribute of respect to our illustrious, president ; 

 and to no one is it more justly due than to Mr. Maclure. 



The West Point mineral occurs principally in lamellar 

 masses ; also, but more rarely, in crystals, which though not 

 very perfect, yet are sufficiently well characterized to enable 

 an observer to refer them to the species to which they be- 

 long. 



The form of the crystals is an octagonal prism, whose angles 

 are about 13b'° and 134°; the terminations are too imperfect 



* Vide Silliman's Journal, vol. v., No. 2, for Mr. H. Seybert's account 

 " of the Maclureite, or Fluo-silicate of Magnesia, a new mineral species." 

 This is the substance called condrodite, which, as Mr. Seybert found it to 

 contain fluoric acid, he judged to be different from the condrodite of 

 Europe. Since that paper was sent for publication, the same chemist has 

 discovered that this acid likewise exists in the European mineral ; so that 

 his proposed name of Maclureite is inadmissible, the substances being the 

 same. 



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