to the hexad axis. The arrangement
of the pyramidal faces n and u in fig. 2 show the hemihedral character
and absence of the full number of planes and axes of symmetry. Fig. 2
represents a highly modified crystal from St Gotthard; a more common
form is shown in fig. 1, which is bounded by the hexagonal prism m,
hexagonal bipyramid x and basal pinacoid c.

In its general appearance, apatite exhibits wide variations. Crystals
may be colourless and transparent or white and opaque, but are often
coloured, usually some shade of green or brown, occasionally violet,
sky-blue, yellow, &c. The lustre is vitreous, inclining to sub-resinous.
There is an imperfect cleavage parallel to the basal pinacoid, and the
fracture is conchoidal. Hardness 5, specific gravity 3.2.

Yellowish-green prismatic crystals from Jumilla in Murcia in Spain have
long been known under the name asparagus-stone. Lazurapatite is a
sky-blue variety found as crystals with lapis-lazuli in Siberia; and
moroxite is the name given to dull greenish-blue crystals from Norway
and Canada. Francolite, from Wheal Franco, near Tavistock in Devonshire,
and also from several Cornish mines, occurs as crystallized stalactitic
masses. In addition to these crystallized varieties, there are massive
varieties, fibrous, concretionary, stalactitic, or earthy in form, which
are included together under the name phosphorite (q.v.), and it is these
massive varieties, together with various rock-phosphates (phosphatic
nodules, coprolites, guano, &c.) which are of such great economic
importance: crystallized apatite is mined for phosphates only in Norway
and Canada.

With regard to its mode of occurrence, apatite is found under a variety
of conditions. In igneous rocks of all kinds it is invariably present in
small amounts as minute acicular crystals, and was one of the first
constituents of the rock to crystallize out from the magma. The
extensive deposits of chlor-apatite near Kragero and Bamle, near Brevik,
in southern Norway, are in connexion with gabbro, the felspar of which
has been altered, by emanations containing chlorine, to scapolite, and
titanium minerals have been developed. The apatite occurring in
connexion with granite and veins of tin-stone is, on the other hand, a
fluor-apatite, and, like the other fluorine-bearing minerals
characteristic of tin-veins, doubtless owes its origin to the emanations
of tin fluoride which gave rise to the tin-ore. Special mention may be