PIGMENT NAME AND
CHEMICAL COMPOSITION 1

rpiment,

•ussian blue, Fe4[Fe(CN)e33

imice (volcanic glass), Na, K, Al, silicate

:algar, As2S2

>d lead, Pb304 0:95%)

pi a, organic

snna, burnt, Fe203, clay, etc.

;nna, raw (goethite), Fe203-H20, clay, etc.

ica (quartz), SiOz

(chalcedony), SiOa
lalt, K, Co(Al), silicate (glass)
rontium yellow, SrCr04
:lc,3MgO-4Si02-H20
tanium barium white, TiCk (25%)

riwjrJiis. i JLJC-O v^r rivjivn

SPECIFIC PARTICLE

GRAVITY 2 CHARACTERISTICS 3

3.4 min. flakes

1.83 colloidal agg.

— vesicular vitr. frag.
3.56 cryst. frag.

8.73 crypt, agg.

— angular frag.

3.56 uneven, round, part.

3.14 uneven spherulites

2.66 cryst. frag.

2.6 crypt, agg.

— splintery, vitr. frag.

— small needles
2.77 platy frag.
4.30 min. round, gr.

tanium calcium white, TiQz (25%)

•fCaS04(75%)

tanium dioxide (anatase), TiOa

(rutile),Ti02
tramarine blue (art.), Nas-ioAleSisO^S^

(nat., lazurite), 3Na2O-
3Al2CV6Si02-2Na2S
tramarine violet

nber, burnt, Fe203 -f Mn02, clay, etc.
iber, raw, Fe203-r-Mn02+H20} clay, etc.
n Dyke brown, bituminous earth
rdigris (copper basic acetate),
:u(C2HA)r2Cu(OH)2
rmilion (art.), HgS

(nat., cinnabar), HgS
idian (chromium oxide, transparent),

lite lead (basic carbonate),
iPbC03-Pb(OH)2
ic white (ordinary), ZnO
(acicular), ZnO
ic yellow, ZnCr04

REFRACTIVE INDEX*
an 2.4 =b, Tif 3.02, fat 2.81 [LB]
i.56«om/i [M*]
c 1.50 (isot.) [M*]
au 2.46,7Lf 2.61, fat 2.59 [LB]
2.42W(w. bi.;pleo.)[M]
(opaque) [M*]
£1.85 (var.) (isot.) [M]
1.87-2.17 (mostly 2.06) (isot.) [M*]
e 1.553, w 1.544 [LB]
«,6>i.54[LB, M*]
1.49-1.52 [M*]
a,/3 (or «) 1.92,7 (or €) 2.01 Q| ext.) [M*]

« 1.539* 7 1.589* 0 1.589 [LB]
n^c 1.7-2.5 [M*]

3.10 prism, or ragged gr. mostly 1.8-2.0 (irr.) (bi.) [M*]

3.9 min. round, gr.

4.2 round, or prism, gr.

2.34 uniform small round, gr.

2.4 angular, broken frag.

— round, gr. (blue, rose,
and violet)

3.64 uneven, round, gr,
3.20 uneven, round, gr.
1.66 irr. amorph. part.

— cryst. frag.

8.09 hexagonal gr. and

prisms

8.1 cryst. frag.

3.32 spherul. gr.

6.70 v. fine cryst.

5.65 v. fine cryst. gr.

— spicules, fourlets
3.46 min. spher. gr.

€ and w 2.5 (w. bi.) [M*]
€2.9, co2.6 [M*]

» MVeen, '-^red GsOt.) [M]

1.50 d= (isot.) [LB]
c 1.56 (isot.) [M*]

mostly 2.2-2.3 [M*]
mostly 1.87-2.17 [M*]
1.62-1.69 [M*]
a 1.53,7 1.56 [M]

COLt 2.81 [M]

cw 3.146, <

a, £s 1.82,7S 2.12 [M*]

€ 1.94, CO 2.09 [M]

6 2.02, CO 2.00 [M]
€ 2.02, CO 2.OO [M*]

1.84-1.9 (irr.; bi.) [M*]

bbreviations: art. == artificial; med. — medium; nat. = natural. The chemical formulas are those commonly accepted
chemical and mineralogical literature, but they may not compare exactly with structural formulas based on x-ray diffrac-
n data or even on critical chemical analysis.
'he figures for specific gravity of the artificial pigments are mainly from H. A. Gardner, pp. 710-712, and those on the
neral pigments are chiefly from E. S. Larsen and H. Berman.
ymmetry terms (monoclinic, orthorhombic, etc.) are omitted because pigments are so finely divided that it is rare when
jervations on crystal symmetry can be made. The term, 'spherulitic, as used here means aggregates that tend toward
lial structure and spherical shape. 'Amorphous' describes materials that are microscopically formless but may be truly
rstalline on the basis of x-ray diffraction data. Abbreviations: agg. = agsregate(s); amorph. — amorphous; comp. = corn-
site; crypt « cryptocrystalline; cryst. = crystal(s);tfrag^= fragment(s); glob. « globule(s); gjr. = grain (s); irr. = ir-
jularjmin. = minute; part. = particle(s); prism. •• prismatic; round. =» rounded; spher. == spheroidal; spherul. =» spheru-
.c; var. « variable; y. = very; vitr. « vitreous.
Jnless otherwise indicated, all refractive index measurements are by sodium light. 25 is the symbol used by H. E. Merwin
indicate greater or less indefiniteness or irregularity In the case of aggregates, especially in respect to refractive index.
>breviations; bi. » birefringent; c = circa; ext. = extinction; isot. «* isotropic: |] — parallel; pleo. == pleochroic; s. «
•onglvj w. p= weakly. The letters in brackets refer to the authorities for the refractive index data: M — H. E. Merwin;
«• H. E. Merwin, data by private communication, hitherto unpublished; W » C. D. West, data by private communica-
nt, Htherto unpubUshed; LB » E. S. Larsen and H. Berman; APL « A. P. Laurie and co-authors.