442 



MINERALOGY. 



Colours of Minerals. 



Colours ! Colours. We begin our description of the exter- 



of mine- nal characters of minerals with that of colour, as it is 

 !* the character which first particularly strikes the eye. 



It exhibits very great variety, and hence its determi- 

 nation is often attended with considerable difficulty. 

 Although it is an important and useful character, it was 

 but ill under-tood before the time of Werner, and it is 

 even at present, by some mineralogists, considered as 

 of little or no value. The older mineralogists had no 

 very accurate nomenclature of colours, and rarely gave 

 any definition of them ; hence it was, that this charac- 

 ter, in their systems, did not afford satisfactory descrip- 

 tions. Some modern mineralogies, particularly those 

 of the French School, use in their descriptions only 

 single, and often unconnected varieties of colour, which 

 is an erroneous practice ; because in describing species, 

 we ought to enumerate all the varieties they exhibit, 

 and in a natural order, so that we may obtain a dis- 

 tinct conception of the arrangement of these varieties 

 into groups or suites that characterise the species. 

 Werner was early aware of the utility of this character, 

 and, by a careful study of all its appearances and varie- 

 ties, was enabled to form a system of colours for the 

 discrimination of minerals, in which he established a 

 certain number of fixed or standard colours, to which 

 all the others could be referred, defined the varieties 

 and arranged them according to their resemblance to 

 these standard colours, and placed them in such man- 

 ner, that the whole colours in the system formed a 

 connected series. 



In establishing the fixed or standard colours, he 

 thought he could not do better than adopt those as sim- 

 ple colours, -which are considered as such in common 

 Principal life ; of these he enumera; es eight, which he denomi- 

 colours. nates chief or principal colours ; they are nihite , grey, 

 black, blue, green, yeilon*, red, and brown. Although 

 several of these colours are physically compound, yet 

 for the purposes of the oryctognost, it is convenient to 

 consider them as simple. 



Werner remarks, " I could not here enter into an 

 adoption of the seven colours into which the solar ray 

 is divided by the prism, as principal colours, nor into 

 the distinction of the colours accordingly as they are 

 either simple or compound ; nor could 1 omit white 

 and black, the former being considered as a combina- 

 tion of all colours, and the latter as the mere privation 

 of light or colour ; for these are distinctions that per- 

 tain to the theory of colours among natural philoso- 

 phers, and cannot be well applied in common life, in 

 which black is ranked among the colours as well as 

 white and yellow ; and green, which is mixed, con- 

 sidered as a principal colour, as well as red, which is 

 simple. 



' In the adoption of the principal colours enumerat- 

 ed above, 1 am countenanced by Dr. Schoeffer, who has 

 exhibited them, with the exception of the grey, in his 

 sketch of a general association of colour, Regensburg, 

 1769. I am, however, justified in adding the grey co- 

 lour, by observing, that it occurs very frequently in 

 the mineral kingdom ; that the attempt to bring it un- 

 der any one of the other colours, would be attended 

 with many difficulties, and that, if we have respect to 

 denominations, it is considered in common life as ac- 

 tually differing from the others." Werner's External 

 Characters, p. 38, 39. 



5 



Each of these principal colours contains one which Oryctogno. 

 is considered pure or unmixed with any other, and 6 T- 

 which is called the characteristic colour : thus, snow- r 

 white is the characteristic colour of white; ash-grey, j 

 of grey; vel vet- black, of black ; Berlin-blue, of blue ; i 

 emerald-green, of green ; lemon-yellow, of yellow ; 

 carmine-red, of red; and chesnut-brown, of brown. 



Werner having thus established eight characteristic 

 colours, he next defined and arranged the most strik- 

 ing subordinate varieties. 



The definitions were obtained principally by occular 

 examination, which enables us speedily to detect the 

 different colours of which the varieties are composed. 

 In detailing the results of this kind of ocular analysis, 

 if we may use the expression, the predominant compon- 

 ent parts are mentioned first, and the others in the or. 

 der of their quantity. Thus apple-green is found to be 

 a compound colour, and we discover by comparing it 

 with emerald- green, that it is principally composed of 

 that colour and another, which is gn-y ish- white ; we 

 therefore define apple-green to be a colour composed of 

 emerald-green and a small portion of grey ish- white. 

 The method he followed in arranging the varieties is 

 simple and elegant. He placed together all those va- 

 rieties which contained the same principal colours in a 

 preponderating quantity, and he arranged them in such 

 a manner, that the transition of the one variety into 

 the other, and of the principal colour into the neigh- 

 bouring ones, was preserved. To illustrate this by an 

 example : Suppose we have a variety of colour which 

 we wish to refer to its characteristic colour, and also to 

 the variety under which it should be arranged. We 

 first compare it with the principal colours, to discover 

 to which of them it belongs, which in this instance we 

 find to be green. The next step is to discover to which 

 of the varieties of green in the system it can be refer- 

 red. If, on comparing it with emerald-green, it ap- 

 pears to the eye to be mixed with another colour, we 

 must, by comparison, endeavour to discover what this 

 colour is ; if it prove to be greyish-while, we immedi- 

 ately refer the variety to apple-green ; if, in place of 

 greyish-tvhile, it is intermixed with lemon- ycilom, we 

 must consider it grass-green ; but if it contains neither 

 greyish- white nor lemon-yellow, but a considerable por- 

 tion of black, it forms blackish- green. Thus, by mere 

 ocular inspection, any person accustomed to discri- 

 minate colours correctly, can ascertain and analyse the 

 different varieties of colour that occur in the mineral 

 kingdom. 



The transition of the principal colours and their va- 

 rieties into each other, he represents by placing the 

 characteristic colours in the middle of a series of which 

 all the members are connected together by transition, 

 and whose extreme links connect them with the pre- 

 ceding and following principal colours. Thus, emerald- 

 green is placed in the middle of a series, the members 

 of which pass, on the one hand, by increase of the pro- 

 portion of blue into the next colour-suite, the blue ; on 

 the other hand, by the increase of yellow into yellow, 

 siskin-green forming the connecting link with yellow, 

 and verdigris green with blue. 



Namet of the Colour t. 



The names of the colours are derived, 1st, From Names of 

 certain bodies in which they most commonly occur, as the colours, 

 milk-white, siskin-green, liver-brown ; 2d, From me- 

 tallic substances, as silver-white, iron-black, and gold- 



