122 Genth and Penfield — Lansfordite, Nesquehonite, etc. 



and after a great deal of trouble found the locality and col- 

 lected every available fragment. Altogether there may have 

 been fifty pieces, the total weight of which did not exceed half a 

 pound. The exact locality is in No. 1 Tunnell at Nesquehoning, 

 four miles from Lansford. All the specimens of the second 

 lot showed a remarkable change. They were not like the first, 

 uniform in appearance, but had suffered partial decomposition, 

 showing at the Itase of the stalactites and incrustations, where 

 they were attached to the carbonaceous shales, groups of trans- 

 parent, radiating, prismatic crystals, individuals of which pene- 

 trated or were wholly covered by the material of the still 

 unaltered lansfordite. During the period of a few months 

 after collecting the second lot at summer temperature, when 

 the thermometer ranged about 90° F., almost all of the lansford- 

 ite specimens suffered a still further decomposition, being con- 

 verted into an opaque white cryptocrystalline or chalk-like 

 mineral, and this change has been continually going on, so that 

 at the time of writing this article there is not a single specimen 

 of wholly unaltered lansfordite in our possession. 



The clear crystals, which we have just mentioned, proved on 

 examination to be a new mineral, having the composition 

 MgCO s . 3H 2 0, to which we have given the name Nesquehonite, 

 aftef the locality where the mineral was found, the Nesque- 

 honing Mine being one of the best known in Pennsylvania. 



In the following pages in addition to the nesquehonite we 

 shall describe a crystallized artificial salt of the same composition.. 

 It will also be shown that the altered stalactites are pseudo- 

 morphs of nesquehonite after lansfordite and from the crystal 

 faces on the stalactites we have been able to make out the crys- 

 tallization of the original lansfordite which is at present only 

 known as pseudomorphs. In making the investigation the 

 chemical ^ork was all done by Dr. F. A. Genth in Phila- 

 delphia, Pa., and the cry stall ographic work by S. L. Penfield 

 in New Haven, Ct. 



Nesquehonite. 



The crystallization of nesquehonite is orthorhombic. The pris- 

 matic crystals occur occasionally isolated but usually in radiating 

 groups, showing only one free end which sometimes projects 

 into a cavity but more often penetrates and is covered with the 

 material of the lansfordite. Individual crystals are frequently 

 over 10 mm long and 2 mm thick, and show at the free end either a 

 basal plane alone or the base in combination with a brachy- 

 dome. The faces in the prismatic zone are always deeply 

 striated parallel to the vertical axis and consequently the crys- 

 tals have their vertical edges rounded and are frequently much 

 distorted owing to the prominence of one or more of the verti- 



