31 
Figs. 13 and 14.— Apatite, Asparagus-Stone, 
PHOSPHORITE, Moroxite. 
The primary form is a regular hexagonal prism 
(Fig. 13), which may he distinctly split in the direction 
of the lateral planes, and with more difficulty in that 
of the terminal planes. Extension of the four lateral 
planes sometimes occurs, so that it becomes a rhombic 
prism; truncations of the basal edges and angles, as in 
Fig. 14, double and treble truncation of these, and also of 
the lateral edges, are also found, so that this mineral 
exhibits, as few others do, the manifold forms of the hexa¬ 
gonal system. It occurs, moreover, in roundish grains, 
mostly of a yellow-green colour, the so-called asparagus- 
stone, as, for example, in the Zillerthal, or in long striated 
verdigris-coloured prisms of the form of rock-crystal—-the 
so-called moroxite, at Arendal in Norway, or in dense 
radiated fibrous or compact masses—the phosphorite, as, 
for example, at Amberg, at Bavaria, in Moravia, and Bohe¬ 
mia, sometimes also in an earthy form, as at Szigette in 
Hungary, and in Spain. 
The colour varies from white to yellow, blue, green, 
red and brown. The crystals are of a vitreous lustre ; in 
the planes of fracture the lustre is resinous, translucent to 
transparent, they are scratched by felspar, and scratch fluor¬ 
spar ; they have, however, the fifth degree of hardness, and 
a specific gravity of 3*1—3*3. The constituent elements 
are basic phosphate of lime, with one-third of an equiva¬ 
lent of fluoride of calcium or fluoride of magnesium. For¬ 
mula, Ca Cl (FI) + 3 Ca 3 P. The powder burns when 
strewed on charcoal, or in a loop of heated platinum wire, 
with a greenish appearance; is not soluble in water, 
readily, however, in nitric acid, without effervescence. 
Before the blow-pipe alone it melts only at the edges: 
with boracic acid and salt of phosphorus, to a clear 
glass; with boracic acid and iron wire, it forms in the 
inner flame phosphuret of iron. Generally found accom¬ 
panied by tourmaline, berylla, tin, etc., in clefts and veins of 
the primary rocks. The finest specimens are those from 
Schlackenwald and Ehrenfriedersdorf, in the Erzgebirge, 
and at St. Gothard. 
The compact-phosphorite has lately been employed as 
a manure instead of bone-dust, and in order to supply 
plants with the necessary quantity of phosphate of lime. 
Phosphate of lime appears to be present in most lime¬ 
stones and marls, as it is known that it is contained in the 
ashes of most plants, and that phosphates have always 
been supplied to animals by the vegetable world. 
PLATE X. Figs. 15—18, and PLATE XL Figs. 1 and 2. 
Fluor-spar, Fluoride of Calcium. 
The primary form is a regular octahedron (Fig. 15), 
which seldom appears, however, in its simplicity; the 
most frequent form is the cube, which usually presents 
crystalline drusy planes (Plate XI., Fig. 1), or is truncated 
at the angles (Fig. 16). Not unfrequently there are 
double truncations of the edges of the cube (Fig. 17), a 
combination of the cube with the pyramidal cube; simple 
truncation of the edges of the cube is more rare (rhombic 
dodecahedron), or the hexagonal pointing of the angles of 
the cube (Plate X., Fig. 18), being the union of the cube 
with forty-eight sided solid. Frequently the crystals are 
aggregated as twins (Plate X., Fig. 17, and Plate XI. 
Fig. 1). Attached crystals also occur (Plate XI., Fig. 2). 
It is, moreover, found dense and granular, especially so in 
the veins of the primary formations, usually along with 
many lead and silver ores, or perfectly compact, as at 
Stolberg on the Harz, and in Cornwall, or earthy as at 
Freiberg in the Erzgebirge, etc. 
The colour varies from white to rose-red, yellow, 
violet, green, and even to a very fine blue ; many crystals 
exhibit dichroism, having by reflected light a yellow or 
blue, and by transmitted light a red or emerald-green 
colour, as, for example, the fine crystals from Derbyshire. 
(Plate X., Fig. 17.) If a pencil of light be allowed to 
fall on such a green crystal, a magnificent cone of blue 
will appear. This property has been called fluorescence . 
The crystals admit of cleavage only in the direction, of the 
octahedron, and present even surfaces of fracture. They 
are vitreo-lustrous, for the most part transparent, of 4*0 
» 
hardness, and 3°0—3'3 specific gravity. The chemical 
constituents are simple fluoride of calcium = Ca FI, or 
51*87 calcium and 48*13 fluorine. Water and weak acids 
have no effect on it; but when powdered, and sprinkled 
with concentrated sulphuric acid, fluoric vapours are deve¬ 
loped, which corrode glass and render it dim. Before the 
blow-pipe it decrepitates, when cautiously heated for some 
time, and afterwards put in a loop of platinum wire, it phos¬ 
phoresces with a blue or green lustre ; also when sprinkled 
over charcoal. It is fusible to a dim pearl, with borax 
and salt of phosphorus to a clear glass, with gypsum to a 
clear pearl, which becomes dim when cooled. The finest 
octahedral crystals, of a rose-red colour (Fig. 15), occur at 
St. Gothard and on the Grimsel; the green varieties in 
Hungary and Siebenburgen; of remarkable size in Grau- 
btindten; the yellow in Saxony; the violet (Plate XI. 
Fig. 1) in Cumberland; those with blue and green play 
of colours in Derbyshire ; very fine groups of cubes, partly 
in combination with the 48-faced solid, are found at Walds- 
hut on the Rhine, and in the Miinsterthal near Freiberg; 
dark blue cubes, with truncation of the angles, at Salzburg, 
and bright green ones at Stolberg in the Harz. Stem¬ 
like, violet and white-striped masses (Plate X. Fig. 2) 
occur at Alston in Cumberland, and are there made into 
all kinds of objects of art—cups, vases, etc. 
Fluor-spar is used principally as a flux for melting 
ores difficult of fusion, which it promotes, and it is from 
its use as a flux that its name has been derived. It is 
used also as an ingredient in enamel, and for the glazing 
of porcelain; further, in the preparation of hydrofluoric 
acid, for the purpose of etching on glass. 
