on a Mineral from near Hay Tor in Devonshire. 39 



are of a browniah red, ferruginous yellow, and delicate white 

 colour. Every crystal has certain planes smooth and splen- 

 dent, while the others are rough and dull, and is either semi- 

 transparent or translucent. The substance scratches rock 

 crystal, and in lustre, colour, fracture, and general appearance 

 closely resembles chalcedony. 



Mr. Robert Cole, a gentleman resident here, who is pas- 

 sionately devoted to the science, has been associated with us 

 in examining the mineral ; and after giving it our best consi- 

 deration, we have been led to conclude that it is crystallized 

 chalcedony. Its hardness, fracture, colour, and close affinity 

 in appearance to that substance, warrant such opinion ; whilst 

 the uniformity of character observable throughout the whole 

 series of specimens, with the perfection and brilliancy of many 

 of the crystals, induce us to believe that the crystallization is 

 original. We are aware that chalcedony has not hitherto 

 been found regularly crystallized ; but this we submit does not 

 present an insuperable barrier to the opinion just expressed, 

 unless a boundary or limit be set up to the operations of na- 

 ture. Chemical analysis, however, might detect some varia- 

 tion fi'om the common constituents of chalcedony, and which 

 might entitle this mineral to be ranged in the catalogue of 

 neiv substances. And with these considerations we contem- 

 plated calling it Haytorite, in honour of its birth-place. 



Some specimens have been presented to Mr. Wm. Phillips, 

 who, with a candour characteristic of true philosophy, imme- 

 diately furnished us with the drawings and measurements form- 

 ing the subject of the ensuing communication, together with 

 some observations of his own. We think it right, however, to 

 state that we have been favoured with an opinion, that the cry- 

 stals are pseudomorphous crystals of chalcedony, since no 

 cleavage can be obtained ; and that, as their figure very nearly 

 approximates that of sphene, it has been conjectured they 

 have derived their form from that substance. In reply to this 

 opinion it may be stated, that no trace of sphene has hitherto 

 been discovered in the mine ; neither have the individual 

 substances of which sphene is compounded, except silex, — 

 unless we take into account the small quantity of lime which 

 is in the garnet. And although no regidar cleavage has been 

 obtained, — the brilliancy, uniformity and jicrfoction of the cry- 

 stals, might incline to the opinion that they are possessed of 

 regular structure, but so constituted as to render it more then 

 ordinarily diflicult to discover. 



We submit tliese observations with much deference : but as 

 they appear to us to stand in the way of the opinion just al- 

 luded to, and to convey a doubt whether the interesting sub- 

 stance 



