21 
Fig. 20.— Wood-asbestus, Mountain-wood, 
Has the look of common asbestus, of a still more brown¬ 
ish-yellow colour, splintery, with the appearance of half- 
rotten wood, and very light and soft; it has a meagre 
feeling, and adheres to the lips when wet. Hardness, 
1*5—2*0. It has the same constitution as asbestus, with a 
quantity of water (about 10 per cent.), and gives, when 
heated in a test-tube, distinct drops of water. It occurs 
at Sterzing in the Tyrol. 
Chrysotyl is distinguished from mountain-wood by 
its remarkable silky lustre and difficulty of fusion; it 
is, however, also a hydrous asbestus. It is principally 
found in delicate plates in serpentine in Moravia and 
Silesia. 
Figs. 21—23.— Serpentine, Ophite, Steatite. 
The crystals are right rectangular prisms, generally 
combined with truncation of the basal and lateral edges, 
as represented in Fig. 21, sometimes also with truncation 
of the basal angles. These, however, are considered as 
pseudomorphs, arising from the metamorphosis of olivine. 
More frequently serpentine occurs in compact masses, 
which form whole mountains, as, for instance, at Julier in 
Saxony and Silesia, The colour varies from yellow and 
green to brown, red, and black; the lustre is very slight, 
resinous; the fracture uneven ; the hardness = 3; the 
specific gravity = 2•5—2 '6. We distinguish between noble 
and common serpentines. The first are always somewhat 
translucent, of purer colour, and fiat fracture ; the latter 
are opaque, dark green to red, brown, and black, or vari¬ 
ously mottled, as seen in Fig. 22. The constituents are 
silicate of magnesia with hydrate of magnesia. It is 
decomposed by acids. 
Calcareous serpentine , ophicalcite or brecciated serpentine 
(Fig. 23), is a mixture of light and dark green serpentine 
and granular white chalk, sometimes aggregated with a 
small quantity of talc. It is found in Corsica and Upper 
Italy, and is applied to all kinds of ornaments, vases, 
pillars, tables, etc.; it takes on a fine polish. 
The finest crystals of serpentine, as seen in Fig. 21, 
are found at Snarum in Norway, where the same mineral 
also occurs in compact masses of a wax-yellow colour, 
with talcose mica, and hydrous talcite. 
The common serpentine , when it occurs in pure, unfis- 
sured masses, is used for altar-pieces, vases, pillars, etc., 
also for all kinds of small articles of household furniture, as 
mortars, candle-sticks, boxes, letter-presses, ink-stands, 
etc., of which there are manufactories in Saxony and 
Silesia. The degree of hardness being small, and not 
being friable, it is easily cut and dressed, and it also 
receives a respectable polish. 
Fig. 24.—Schiller-stone, Eclogite, or Omphacite. 
Schiller-spar or diallagite is a hornblende mineral, 
which occurs in green crystalline laminated granules, with 
oblique-angled fracture of the plates, very seldom by itself, 
but usually with garnet or a little granular quartz, as 
represented in Fig. 24. This stone has received the name 
of omphacite or eclogite , and is principally found at Hof and 
Gefrees in the Fichtel Mountains, at the Sau-Alps in 
Carinthia, and in Norway and other localities. In ser¬ 
pentine it is found at the Harz, in Saltzburg, and in 
Tuscany. The pure schiller-spar is splintery in fracture, 
of a vitreous to a metallic lustre, translucent, green to 
brown and blackish, difficultly fusible. It has a hardness 
of 3*5—4*0, and a specific gravity of 2*65—2*70. Bronzite, 
anthophyllite, and disterrite are allied hornblende mine¬ 
rals. The constituent elements are silicate of magnesia, 
with silicate of the protoxide of iron, and lime. 
III. FELSPATHIC MINERALS. 
These minerals play an important part in the mineral 
kingdom, in so far as they not only enter into it in the 
most varied forms, but they also constitute an essential 
element in the earth’s crust, and by their decomposition 
under the influence of air and water, afford to the soil 
a constant supply of potass and soda salts, from which 
the vegetable world draws the alkaline salts necessary to 
the growth of plants. Further, there exist sometimes 
beds of clay and marl which, when mixed with sand and 
felspathic minerals, form an excellent soil for raising most 
vegetables. All felspars are combinations of siliceous clays 
and siliceous alkalis of crystalline structure, with obliquely 
angular foliated fracture. The hardness is = 6; they 
therefore, when struck with the steel, give off feeble sparks, 
and can only be scratched by a knife with great difficulty. 
Thus, too, they are but little friable, and impart to those 
rocks, the principal element of which they form, a certain 
solidity and durability. They contain no water; they 
take it up, however, and lose the freshness of their lustre 
in proportion as they are decomposed, while at the same 
time the alkaline elements are given off; this is the source 
of basic siliceous potash, soda, etc., and siliceous hydrate 
of alumina (clay). Before the blowpipe, fine splinters 
melt to a transparent, usually colourless bead, which, when 
wetted with a solution of cobalt, and heated anew, takes 
a fine blue colour. If held in the blue flame of the blow¬ 
pipe by means of platinum forceps, the potash felspars 
colour the flame violet, the soda felspars colour it yellow, 
the lithium felspars purple-red, and the calcareous spars 
vermilion-red. In the mixed felspars, the yellow colour 
of the soda felspars generally preponderates. The specific 
gravity is between 2*50 and 2*76. The colour is accidental 
in them all, for in a pure state they are colourless ; there 
are, how r ever, red, green, and blackish-grey felspars. 
