Merrifield, Mary P.: The art of fresco painting, as practised by the old Italian and Spanish masters, with a preliminary inquiry into the nature of the colours used in fresco painting: with observations and notes (London: Charles Gilpin, 1846)

XX

OF THE COLOURS USED

friable, hard, black, and smooth, without either gritty parts or
veins.
“ That commonly used by the painters is factitious, being made of
Armenian bole, and other drugs. The common native or the fossil
kind comes from Bohemia, &c. This assumes various forms :—
spherical, pyramidal or cellular, and is composed of small pyramids ;
the apices of which appear in a tranverse section in the centre. It
contains a large portion of iron, but the iron is obtained with such
difficulty and is of so bad a quality, that this ore is not commonly
smelted. This stone, when exposed to a moderately strong fire, falls
by degrees into scales, and in this state is attracted by the magnet,
and gives out its iron to acids. The gilders use it for burnishers to
polish their metals. Bauschius has an express treatise, on the Lapis
Hematites.”—See Chambers’ Dictionary.
The following is Jameson’s description of Red Haematite or Fibrous
Red Ironstone. Its colour is usually intermediate between brownish
red and dark steel grey. Some varieties incline to blood red, others
to dark steel grey, and others to bluish. It occurs most frequently
massive and reniform ; also botryoidal, stalactitiform and globular.
The external surface is generally rough and glimmering, seldom
smooth and shining. Internally it is usually glistening, which some-
times passes into glimmering and the lustre is semi-metallic. The
fracture is always fibrous, and is straight, delicate and stellular or
scopiform. The fragments are commonly cuneiform, seldom as in
the coarse sorts, fibrous or splintery.
It generally occurs in distinct concretions, which are large, small or
fine, angular, granular and traversed by others which are curved,
lamellar more rarely, it occurs in cuneiform prismatic concretions. The
surface of the concretions is either smooth or streaked, and the
colour inclines to iron black, with a shining and metallic lustre.
The streak is always blood red ; it is hard, passing into semi-hard;
it is brittle; it is rather easily frangible; it is heavy, inclining to
uncommonly heavy. Specific gravity, 4.740, Gellert; 5.005,
Kirwan; 4.8983, Brisson ; 4.840, Wiedemann ; 5.025, Ullman.
Its constituent parts consist of—Oxide of Iron, 90 ; Trace of
Oxide of Manganese, 0; Silica, 2; Lime, 1; Water, 3; = 96.—■
Daubuisson, Ann. de Chimie, 1810.