440 N. L. Bow en — Cacoclasite from Quebec. 



Art. XXX. — Cacoclasite from Wakefield, Quebec; by 



N. L. Boweet. 



In 1883 crystals of a mineral found in blue calcite near 

 Wakefield, Quebec, were described by Lewis 1 and given 

 the specific name cacoclasite. Later they were further 

 investigated by Genth in particular, 2 who proved that the 

 crystals were made up of a mixture of materials and 

 were, therefore, pseudomorphs and not entitled to rank 

 as a mineral species. Genth's chemical investigation led 

 him to believe that the crystals were a mixture of quartz, 

 calcite, apatite and material of indefinite composition 

 and that they were pseudomorphs after scapolite. Caco- 

 clasite is apparently peculiar to this Canadian locality. 



In looking over some material from Wakefield in the 

 University collection, fine specimens of this cacoclasite 

 were noted and in checking their nature under the micro- 

 scope it was found that the mixture represented does 

 not correspond with that deduced by Genth and is, in 

 fact, considerably simpler. The material was examined 

 in powder form in immersion liquids, a method that is 

 particularly well adapted to the identification of the con- 

 stituents of a fine-grained mixture. Cacoclasite may 

 have crystals of other minerals coating its surface and 

 these may project into it but, if a crystal free from such 

 foreign material is selected and crushed for microscopic 

 examination, it is found to consist of only three minerals. 

 Calcite (w = l-66) is fairly abundant and apatite (n — 

 1-645) is present in small amount but the main constitu- 

 ent is an isotropic substance of index 1-74. No quartz 

 is to be seen. If some of the powder is warmed with 

 hydrochloric acid, calcite and apatite are removed and 

 the residue is made up entirely of the isotropic substance. 

 This substance shows no sign of cleavage and even after 

 boiling with strong HC1, there is no suggestion of attack. 

 It is evidently the mineral grossularite. 



That the cacoclasite consists of grossularite, calcite and 

 apatite is borne, out in a most striking manner by Genth's 

 analyses. He gives two analyses of which that numbered 

 I was made on the "best" material. It is given below 

 together with a recalculation of the mineral constituents 

 represented. 



^roc. Acad. Phila., 1883. 

 2 This Journal, 38, 200, 1889. 



