ORYCTOGNOSY. 
a ; beryl, pitch- ee green lead ore, fullers’ earth :— 
fifkin green, ne lead ore, uran n mica, green iron earth. 
Yellow.—Of this banat yellow is the pureft tint. Sul- 
phur yellow ; a {ulphur, yellow ferpentine air ea el- 
low; copper pyrites, pale yellow native gold :—ftraw yel- 
low ; calamine, yellow earthy cobalt :—bronze or ber 
yellow ; —wax ellow ; common opal, yellow 
lead ore :—honey y ello w3 honey ftone or mellite, amber :-— 
lemon yellow ; cle orpiment, fome varieties of pha 
lead ore: —zol ye ; deep yellow native gold, copper 
pyrites:—ochre yellow; yellow earth, calamine, ochrey 
i one :—«ine .ye tee Saxon i fluor- 
fpar :—ifabel or cream yellow n {par, calamme, mo 
tain cork :—orange yellow ; ine red lead ore nia 
of se i 
—Its pureft variety is carmine red. Aurora red; a 
variety, of realgar, blende from Scharfenberg = lvacath 
t: i—tile —_ tile ore, common clay, 
; light red cinnabar :—blood 
red ; Bohemian. garnet, light ced filver ore, alee com- 
jafper : —copper red ; carmin 
fi red; feldfpar, brown fpar, indurated lithomarge of 
Rochlitz :—cochineal red; dark red copper ore, dark r 
cinnabar mfon red; noble garnet, amethyft-fapphire : — 
noble garnet, red cobalt :—cherry red; red antimony from 
Braunfdorf, red iron- eee :—brownifh-red ; common clay 
iron-ftone, common jafpe 
rown.—Its’ molt ial variety is blackifh-brown. 
Reddifh-brown ; tin-ftone, brown blende :—clove brown; 
brown iron-ftone, a variety of foal cryftal:—hair brown ; 
wood tin, wood opal :—broccoli brown; zircon :—chefnut 
brown; Egyptian be ei jafper :—yellowifh-brown ; 
l -ftone, brown blende, cat’s eye :—pinch- 
brown ; brown earthy cobalt, femi-opal :—b! ackith-brown ; 
= copper black, brown coal, &c. 
» Shade or Intenfi ity of Colour.—Colours may be deter- 
Pret by the relation in which they ftand to each other, 
with regard to intenfity or fhade. Thus, among the prin- 
cipal colours there are fome which are light, fuch as white 
and yellow; and fome which are'dark, as blue and black. 
And, befides, the varieties of the principal colours differ 
from, each other in re{pect to fhade: thus, ainong the blue 
colours, indigo blue is dark, azure blue clear, and fky blue 
light ; and even the varieties may afford a diverfity of fhade, 
as, for inftance, ae fifkin green, light fifkin green. The 
peculiar fhade o ur in a mineral 1s frequently owing to 
its greater or lefs Gages 3 the palenefs being in pro- 
portion to the — of a soca and the ce to 
The degree of RA = in mi- 
et 
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fenic an 
divided into, (a), fimple tarnifhed colours: wiz. grey, as in 
white cobalt ; black, as in native arfenic; brown, as in na- 
tive filver, copper pyrites 5 reddifh, as in native bif{muth; 
yellowifh, as in white cobalt ore: and, (6), variegated tar- 
nifhed colours, the varieties of whic 
€ or pigeon-neck tarnifh, 
as in bifmuth; and tanger fteel tarnifh, as in fpecular 
iron. 
4- The Play of Colours.—By this is underflood the pro- 
perty which fome minerals poffefs of refraGing from par- 
ticular {pots the different rays of light. The e play of colours 
na mineral can only be obferved in fun-fhine, or in a ftron 
light. It 1s remarkable in the diamond, the rock cryftal, 
c. 
The mutable R 
cf Reftedtion of Colour. —This is diftinguifhed 
from the play o 
colours, by the mineral exhibiting in the 
ame {pot a change of colour, according to the pofition of 
its furface being varied, producing a different angle with 
the incident rays of lig is mutable refleCtion is either 
uperficial, as in Labrador oe 3; or internal, as in common 
opal, dichroit or iolite 
utation of Colour —This is diftinguifhed from 
the ral, in which latter the furface only undergoes a 
change of colour; but in the mutation of colour, the effe@ 
carious the mineral, and fometimes pervades the whole. 
This affurds two el tes : (a) the fading of colour, by 
: (d) the perfee change of ‘led is pe the confe- 
quence of fading, when one colour is loft, a new one 
appears, as in light coloured {parry iron fone and earthy 
grey manganefe. 
rE Detain of Colours.—Thefe are obferved on fimple 
minerals ; pecimen containing feveral colours 
which a ciouah its interior, according to certain deli- 
— : viz. dotted ; 
ct 
3 
ter 5 pete are either round and regular, o 
lar :—nebulous or 
orm entric cade as in flint mpd eee ies 3 
wa oe clinestion pinhead the ener ie of a tree: 
—ruin-fhaped ; as in the Florentine marble :—veined ; as in 
various seein ferpentine &c. Many of thefe feem to 
cae no defini 
ped os fi fon tof the Particles.—-According to this pro- 
ae e divided into folid, friable, and fluid; 
but ee cropenies alfo belong to the particular generic 
characters of minerals, to be afterwards defcribed. 
Particular generic CharaGers of Solid Minerals. 
The external Afpe&.—In the external appearance or 
ice of a mineral, three things are to be obferved; the 
a fhape, i oo {urface, and the external hilire: 
« The external is is divided into common, par- 
rears regular, a penis external form. 
ommon external Form.— a mineral is faid to 
be when it exhibits no refemblance to any known fub si 
