466 



M I N E R 



Oryctogno. 



y- 



It is observed either when 



^ 1. Spontaneously emitted, in which case it is 



>> " *"Y"^ a. Bituminous, as mineral oil and mineral pitch. 



b. Faintly sulphureous, as natural sulphur. 



c. Faintly bitter, as radiated grey antimony. 



2. After breathing on it, in which a clayey-Hike smell, 



as in hornblende and chlorite, is produced. 



3. Excited by Friction. 



a. Urinous, in stinkstone. 



b. Sulphureous, in iron pyrites. 



c. Garlick-like, or arsenical, in native arsenic and 



arsenic pyrites. 



d. Empyreumatic, in quartz and rock crystal. 



VIII. CHARACTERS FOR THE TASTE. 



Characters This character occurs principally in the saline class, 

 for the f or wn jch it is highly characteristic. 

 The varities of it are, 



1. Sweetish taste, common salt. 



2. Sweetish astringent, natural alum and rock but- 



ter. 



3. Styptic, blue and green vitriol. 



4. Saltly bitter, natural Epsom salt. 



5. Saltly cooling, nitre. 



6. Alkaline, natural soda. 



7. Urinous, natural sal-ammoniac. 



II. PARTICULAR GENERIC EXTERNAL CHA- 

 RACTERS OF FRIABLE MINERALS. 



Particular The external characters of friable minerals form a 

 generic ex- particular Section in the System, because they exhibit 

 ternal cha- var j et i es ant i kinds that do not occur in solid minerals, 



fria'bie mi- and manv of * he cnaracters of solid minerals > sucn as 

 nerals. fracture, distinct concretions, streak, hardness, and 

 frangibility, and others_ are wanting. 



1. The External Shape. 



The exter- j n friable minerals there are but few external shapes- 

 al shape, f^g j; ve f o n ow ; n g kinds are all that have been hitherto 

 described by naturalists. 



1. Massive, as in porcelain earth, and scaly red and 

 brown iron ores. 



2. Disseminated, as in earthy azure copper, and blue 

 iron earth. 



3. Thinly coaling or incrustins. It is analogous to 

 the form in membranes. Examples, Copper-black, or 

 black oxide of copper. 



4. Spumous. When a friable mineral appears like 

 froth resting on a solid mineral, as is sometimes the 

 case with scaly brown iron ore. 



5. Dendritic, also in scaly brown iron ore. 



II. The Lustre. 



The lustre. It is determined in the same manner as in solid mi- 

 nerals ; we have here, however, the following distinc- 

 tions. 



1. In regard to Intensity. 



A. Glimmering, which is either strong or feeble, 

 as in scaly brown iron ore, and porcelaiu- 

 Karth. 



B. Dull, as in black cobalt ochre. 



2. In regard to the soil of lustre 



A. Common glimmering, as in scaly and brown iron 

 ores. 



B. Metallic glimmering, as in scaly red and brown 

 iron ores, and Pearly glimmering, as in earthy 

 talc. 



3 



A L G Y. 



III. The Aspect of the Particles. 



The particles of friable minerals appear in some in- _ -,_ 

 stances like dust, so that we can with difficulty dis- Theav pect 

 tinguish by the naked eye any dimensions ; these are of the par- 

 called dusty particles, and occur in cobalt crust, blue tides. 

 iron earth, and porcelain earth ; in others, two dimen- 

 sions can be observed when they appear foliated, and 

 these are called scaly particles, and occur in scaly brown 

 and red iron ores, earthy talc, and chlorite earth. 



IV. The Colouring or Soiling. 



Friable minerals colour either strongly, as in scaly The co- 

 red and brown iron ores, and porcelain earth ; or louring or 

 slightly, as in black cobalt ochre. soiling. 



V. The Adhesion to the Tongue. 



This character occurs only in those friable minerals The adhe- 

 which are cohering. It varies in intensity, being ei- sion to th 

 ther feeble or strong. tongue. 



VI. The Friability. 



Friable minerals are either loose, that is, when the The friabl- 

 particles have no perceptible coherence, as in blue iron lity. 

 earth ; or cohering, in which the particles are slightly 

 connected together ; they are either feebly cohering, as 

 in porcelain earth, or strongly cohering, as in potters 

 clay. 



III. PARTICULAR GENERIC EXTERNAL CHA- 

 RACTERS OF FLUID MINERALS. 



Fluid minerals possess fewer characters than friable Particular 

 minerals. The following four are all that occur. generic ex 



1. The lustre is either metallic, as in mercury; or ternal cha - 

 resinous, as in rock oil. The lustre is always splen- fl^mi-'' 

 dent. nerals. 



2. The transparency. The following are all the de- 

 grees necessary for the purposes of discrimination. 

 1. Transparent, as in naphtha. 2. Troubled or turbid, 

 as in mineral oil ; and, 3. Opaque, as in mercury. 



3. Thejluidi/y. Here we have only two degrees to 

 observe. 1. Fluid, as in mercury and naphtha. 2. Vis- 

 cid, as is sometimes the case with mineral oil. 



4. The netting, by which we understand the wetting 

 of the fingers when they touch the mineral. It is ana- 

 logous to the soiling in solid and friable minerals. 

 Mineral oil wets the finger, but mercury does not. 



ON DESCRIBING MINERALS. 



Most of the species exhibit many varieties of cliarac- On desrr 

 ter, which are generally distributed throughout a num- ing minei 

 ber of individual specimens ; hence it follows, that in als. 

 order to obtain a distinct conception of a species, we 

 must examine not one, but many different specimens 

 of it. The descriptions of the species may be executed 

 in the following manner. 



The fol'owing description may serve as an example 

 of the mode of arranging the external characters. 



Pi'eciuHS Gurnet. 



External Characters. All the colours of this mineral Pre 

 are deep-red, which always inclines to blue ; the prin- ga n 

 cipal colour is columbine-red, which passes into cherry- 

 red, and blood-red, and it appeals even to run into 

 brnnnifk-red and hyacinth-red. 



It rarely occurs 'massive, sometimes diistminaled, in 

 angular pieces, and in UimAlar concretions ; but most 



Oil* 



et. 





