1830.] 
of the Turquoise Mines , in Persia. 
377 
he restores in calaite the name under which it was known to Pliny (calais,) and 
distinguishes a “ blue conchoidal” and a “ greenish quartzv variety to which he 
assigns the names of agapkite and Johnite, with a passion for multiplying names 
too often to be found among mineralogists. The genuine 
by professor John, of Berlin, who found its specific gravity 2,860, and composition 
as follows : 
Argil, 'd, 
Oxyde of copper, 4,5 
Water, 18, 
Oxyde of iron, 4, 
Lead and loss, b,5 
100 
The other varieties hove not, it appears, been examined ; but the specific gravity 
of the agapbite has been set down as from 3. to 3,25, and the colouring matter was 
suDDOsetfhv Gahn to he arsemate »/ir«. But the specific gravity of tl c oiWohre, 
suppose cl tiy vaa » colouring matter has been ascertained to be phos- 
TZ M “’ri^i. S^SX%«lfi>en examined by Gahn was of this 
species" Fischer suggests that the Johnite may contain much silex, from its 
confirmed by Fraser's account, prove that all 
the varieties white, blue, and green, are but gradations of the same mineral . whe- 
ther such a* conclusion is borne out by chemical analysis, remains to he examined, 
thei such a com. observed d fferences ot colour, lhe hard- 
*ey are not scratched by quarts. 
^Havtag^woXupon wrS “ m!dl Unions of the mineral in tlie following exa- 
minatioif 1 do not give the quantities as rigidly correct ; the operatmas were hardly 
quantity of water, by heating the 
of freed alkali t>r acid. 
Mineral. Hater, per cent. 
No. 
1 . 
2 . 
3. 
White friable turquoise, 
Precious bine ditto, 
Bright green variety, en-1 
crusted with pyrites, J 
19 , 
18,62 
18, 
4 Decomposing white feldspar, 4, 
*' 1 • 1 * a_ fU 1 llO 
Acid. 
trace of acid, 
perfectly pure water, 
litmus hardly reddened when 
the. specimen was clean ; 
when otherwise, much sul- 
phuric acid was given otf. 
reddening litmus slightly. 
“5 !‘"h 3s7hat the water was a definite ingredient in the 
From the .above trials, it see n hat e wate^ ^ ^ ^ p(Jr ceB , 
three first minerals, being ' t ( [je fe i dspar bears the same proportion to the 
alumhia' oHliat mineral, as 18* does to the alumina of the turquoise, or 80 . 18,5 
; ^Lse‘ proportions nearly correspond with an afognic .compound of 2 parts 
" ;Uer, an,d the nature of the metallic colouring 
“ f ° ,l0WS ^ 
No '*' becoming emerald green when any of 
the outer crust was taken up. 
nittn li<rht green blue — emerald green glass. 
a SllSht ^ 
2 . 
5. 
3. 
6 . 
of gi*een. 
4. Feldspar— pale yeHowi? = .* ts was that the blue heads were co- 
The first impression upon i these expe i and the brown by iron; 
loured by a minute portion of coba.t, tt e g o ^ tbo ‘ e met als in aJ l treatises uppn 
as such are the colours ascubed * > comparative assays with the pure 
the blowpipe. However, upon making a sei les 01 i 
