26 
two equivalents of water, Na Si + Al Si + 2 H. The 
yellow and red-coloured varieties always contain a small 
quantity of oxide of iron. Fine needles melt readily in 
a flame to small globules, and still more readily before the 
blowpipe into blebby pearls, and give off water; with 
greater difficulty they can be melted into a white glass. 
They colour the flame always yellow, and with salt and 
phosphorus they leave a skeleton of silica. Scolezite, which 
occurs in the Faroes and in Iceland, contains, instead of the 
silicate of soda, silicate of lime, and reddens the flame. 
There exists, however, a soda and lime zeolite, which has 
been called mesolite. The finest natrolites are found in 
crystals in Auvergne and in Bohemia, in radiated bundles 
in Iceland and the Faroes, the radiated natrolite occurs in 
clefts of the clink-stone at Hohentwiel, Magdeberg, and 
Hohenkraken in the Hogan; that from the latter locality 
has been polished as marble. Natrolite especially is an 
essential ingredient in clink-stone. 
Fig. 4.— FIeulandite, or Oblique Rhombic 
Foliated Zeolite. 
The primary form is an oblique rectangular prism, and 
occasionally right rhomboidal and oblique rhombic prisms 
occur, with different truncations of the edges and angles, 
as, for example, in Fig. 4, in which the acute basal and 
lateral edges of the monoclinic prism are truncated. The 
crystals are easily split in the direction of the rhomboidal 
planes, and present a remarkable foliated structure; they 
are transparent to opaque, of vitreous or pearly lustre, 
generally colourless, reddish to tile-red, friable, moderately 
hard (3*5—4), of 2'2—2'3 specific gravity, soluble in acids. 
The ingredients are silicate of lime with silicate of alumina 
and water. Formula Ca Si + 4 Al Si 3 + 18 H. Fuses 
before the blowpipe with intumescence to a white enamel, 
and colours the flame a yellow-red. On charcoal it gives 
off much water. This mineral is frequently confounded 
with stilbite, to which it bears some resemblance in appear¬ 
ance, hardness, lustre, and chemical constitution, and 
deportment before the blowpipe ; it may be easily distin¬ 
guished from it, however, by the form of the crystal, since 
stilbite belongs to the right rhombic system. It occurs 
principally in amygdaloid and diorite, as, for example, in 
the Fassathal (here it is tile-red) in Bohemia, in the Faroes, 
and Iceland ; it is also found, however, in gneiss and mica 
in the United States, at Kongsberg in Norway, and in 
the clay-slate at Andreasberg. 
Fig. 5.—Stilbite, Foliated Zeolite, Desmin. 
The primary form is a right rectangular prism, and it 
is usually found with truncation of the basal angles, as in 
Fig. 5, aggregated in wedge-shaped fasciculi, and radiated 
to foliated, in twins, etc. The crystals are striated on the 
sides, and may be easily split in one direction; the hardness 
is 3*5—4, and the specific gravity 2T5—2-20. They com¬ 
port themselves like heulandite before the blowpipe and 
with acids, and are generally colourless, passing into grey 
and brown-red. The chemical constituents are likewise 
lime with silicate of alumina and water, according to the 
formula Ca Si + Al Si 3 + 6 H. The localities are the 
same as those of the foregoing mineral, especially in the 
Faroes and Iceland, also in Scotland, Ireland, at the Hartz 
Mountains, and at St. Gothardt, etc. The following are 
also monoclinic lime zeolites ; the laumonite or lomonite 
= Ca° Si 3 + 4 Al Si 2 + 18 H; the leonhardite ~ 3 Ca 
Si 3 + 4 Al Si 3 + 15 H. 
The epistilbite is rhombic = Ca (Na) Si + 3 Al Si 3 + 
5 H, so also are the thomsonite = (Ca, Na, K) 3 Si + 3 Al 
Si + 7 H, the prehnite Ca 3 Si + Al Si + H, and the 
CaR 
phillipsite = ^ \ gj 3 + 4 A} s'p + is H. 
The schubasite crystallises in rhombohedrons, as Fig. 
9 and 10, frequently in twins, of 44)—4-5 hardness, and 
2-0—2T7 specific gravity. The elements are (Ca, Na, K) 
Si 3 + 3 Al Si 3 + 18 H. It occurs pre-eminently at Stei- 
nau in Kurhessen, at the Kaiserstuhl, at Aussig in Bohe¬ 
mia, at Oberstein, in the Faroes, and in Scotland. The 
cross-stone or harmotome is a baryte and potash zeolite, 
which crystallises in right rectangular prisms, frequently 
aggregated in quadruplets of 4*5 hardness, and 2'39—2*43 
specific gravity. It is found at Andreasberg iff the Hartz 
mountains, at Strontian in Argyllshire, and at Old Kil¬ 
patrick, Dumbartonshire, at Oberstein, etc. Formula = 
2 Ba-\ 
V 3 Si 4, + 7 Al Si' 2 + 30 II. 
Fig. 6.—Amalcime, Cubizite, Sarcolite. 
The primary form is the cube, in the planes of which 
the crystals may be split; triple sharpening of the angles 
usually occurs, however, as in Fig. 6, so that at last perfect 
icositatetrahedrons arise as in the leucite. The crystals 
sometimes reach the size of the hand, and are usually 
reddish, passing into grey and white, translucent, ef a 
vitreous-pearly lustre, of 5*5 hardness, and 2’06 specific 
gravity. Constituents : Na 3 Si 3 + 3A1 Si + 6 H ; it is 
therefore a soda zeolite, which crystallises in the regular 
system, and, before the blowpipe colours the flame distinctly 
yellow. It is easily fusible, and soluble in acids. It is 
found principally in the Fassathal, at Etna, in the Faroes, 
at Brewig in Norway, also in the trachyte of the Kaiserstuhl, 
where it has been confounded with the leucite. 
The faujasite is a lime and soda zeolite, which crystal¬ 
lises in regular octahedrons, of vitreous to adamantine 
lustre, of 5*5 hardness, and T923 specific gravity. For¬ 
mula : (Ca, Na) Si 4 + 3 Al Si 3 + 8 H. Is found in the 
amygdaloids of Sassbach, and at Annerode in Hesse, where 
it occurs with phillipsite in a porous basaltic lava. 
Figs. 7 and 8.—Apophyllite, Ichthyophthalmite 
Albine. 
This mineral crystalises in right square prisms, in 
general combined with truncation of the angles, as seen in 
Fig. 7, or in quadratic pyramids, more rarely in quadratic 
tables with truncation of the angles, or in foliated masses, 
