AIETALLINE MLNBRALS. 63 



bismuth, having similar values for H and v, oi' which i'mplect'it.o may be taken as an 

 example, constitutes the genus Emplectites. 



The Pyritoideœ include two x^rincipal genera ; Pyrites ( H = o'ô — G'ô : ii ^ 4 — -t"5), 

 comprising- sulphids of iron, cobalt, nickel, copper, chromium and ruthenium ; and 

 Pyritinus ( H 3-5 — 40 : y = 47 — ô'ô), also of sulphids of iron, nickel, co^iper, with 

 manganese and tin. ^ 



The tribe Smaltoideœ, embracing various arsenids and antimonids, includes the genus 

 8maltites ( H = 5 — 6 : y = 4'5 — 5'5 ) made up of arsenids of iron, nickel and cobalt, 

 of which leucopyrite and smaltite are types, while the antimonial species, breithauptite 

 is closely related. The arsenids of copper, with less hardness and a highi'r value of v, 

 will form another genus, Algodonites, near to which is the antimonid of copper, hors- 

 Ibrdite, and the antimonial silver, dyscrasite. 



Tlie Arsenopijriloideœ include the genus Arsenopyriles ( II = 5 — G : t; = 4i") — Ô'S), 

 embracing the double sulphids of arsenic, with iron, cobalt and nickel, of which mispickel 

 or arsenopyrite is a type. Closely related thereto are the double sulphids including 

 antimony and bismuth, of whi<h ullmannite, corynite, alloclasite and grunauite are 

 examples. 



In the Spatometalline^'E are comprised various forms of siilphur, selenium and 

 phosplioriis. The Sphaleroideœ include the genus Sphalerites, ( II = 2-5 — 4'0 : v = 6 — T ) 

 embracing sphalerite, wurtzite, greenockite, hauerite, oldhamite, cinnabar, and the 

 arsenical sulphids, realgar and orpiment. Here also proliably belongs the red antimonic 

 sulphid. The Proustoideœ include the genus Pyrargy rites ( H ^ 2 — 3 : d = 8 — 9) in 

 which we place both arsenical and antimonial red silver ores — proustite, pyrargyrite, 

 miargyrite, polybasite, etc. In this tribe also is placed Tennantites ( H = o'ô — 4%5 : 

 V = 6'5 — Yo ) including the various species of fnhlerz. with binnite, dufrenoysite, 

 livingstonite, etc. 



The hardness ( H ) and the values of v have here been given approximately. The 

 paper presented includes all the species of this order, together with tables giving the 

 chemical formiihr, crystalline forms, hardness, specific gravity, and the calculated A'alue 

 of p and V, besides a binomial Latin nomenclature, of which examples were given. 



