484 L. V. Pirsson — Fowlerite variety of Rhodonite. 



Art. LXIII. — On the Fowlerite variety of Rhodonite from 

 Franklin and /Stirling, JY. J. ; by L. Y. Pirsson. 



The zinc-bearing rhodonite of Franklin and Stirling Hill, 

 ]ST. J., has long been known under the name of Fowlerite. It 

 was, so far as can be learned, first mentioned by Fowler* in 

 1825, who speaks of a red siliceous oxide of manganese, which 

 had been lately observed by Dr. Thos. Nuttall. It was also 

 described by Thomsonf in 1828. Analyses also have been 

 published by Hermann,:}; Rammelsberg§ and Camac.|| 



The crystal form and physical properties of this variety of 

 rhodonite have not been thoroughly investigated. It is, how- 

 ever, important to our knowledge of the species that this should 

 be done, in order to determine how far a departure from the 

 normal type, if any, the introduction of the zinc has caused. 

 A new chemical analysis, upon some of the very fine material 

 which within a few years past has been brought to light also 

 seemed desirable. It is with these objects in view that the 

 present investigation has been made. 



The mineral occurs imbedded in . calcite, in the outer walls 

 of the mines and it is when these are broken into, in the pro- 

 cess of working, that the best specimens have been obtained. 

 The crystals occur of all sizes, from four inches long by one in 

 width and thickness, to individuals of microscopic dimensions 

 and also in large masses crystalline in structure and possessing 

 characteristic cleavage but without crystal faces. Upon dis- 

 solving away the calcite covering these lumps, with hydro- 

 chloric acid, a side will often be found which is completely 

 covered with interlaced masses of small crystals. The larger 

 crystals also occur in these confused masses and during the 

 past few months, there has been a magnificient specimen of 

 this mineral on exhibition, in New York, consisting of a large 

 group of well formed crystals of the largest size. 



The color in general is a beautiful rose-pink and in small 

 and perfect crystals the mineral is transparent. The smaller 

 ones are much more homogeneous than the larger individuals, 

 the latter being often pitted with inclusions of calcite and other 

 material. All specimens that have been observed are com- 

 pletely permeated with cleavage cracks, even those of micro- 

 scopic size. As a result of this the mineral is extremely brittle. 



Like most minerals associated with calcite, the luster of the 

 crystal faces is almost entirely wanting. When present it is 

 seen on the basal plane, the prisms and the 2 (221) pyramid ; 



*This Journal, I, ix, 245, 1825. f Ann. Lye. N. T., iii, 28, 1828. 



% Journ. pr. Chem., xlvii, 6. § Min. Chem., 459. 



|| This Journal, II, xiv, 418, 1852. 



