before the Blp and turns yellow; pyrochlore does not swell and becomes grayish. Opal-SiO3+xHO. Before the Blp yields water and becomes opaque; fuses with carbonate of soda to a clear bead, with effervescence. Infusible. Boiled with hydrate of potassa, it dissolves completely or to a great extent; the solution gives a gelatinous precipitate with chloride of ammonium. Hardness-6-6.5.

Xenotime=3YO,PO5. Color, various shades of brown or flesh-red. Hardness-4-5. Gives the phosphoric acid reaction, § 94. Infusible. With salt of phosphorus dissolves with great difficulty to a colorless glass.

[See also Childrenite and Orthoclase.] Section 2. Hardness=7, or above.

[See Cassiterite, Rutile, and Opal of the preceding
secțion whose hardness sometimes approaches 7.]
Quartz=SiO3. The various varieties of quartz, as
rock-crystal, amethyst, hornstone, flint, chalce-
dony, &c., are infusible and unalterable before
the Blp, and fuse with carbonate of soda to a
transparent bead, with effervescence. Hard-
ness=7.

Iolite=2 (3[MgO.FeO], 2SiO3) + 5(Al2O3, SiO3) ;
Staurotide=2(Al2O3. Fe2O3), SiO3. Hardness=

7-7.5. Do not fuse to a transparent glass with
carbonate of soda. Fusibility of iolite=5-5.5;
color blue, grayish. Staurotide is infusible;
color brownish-red, brown; crystals often cruci-
form.

Beryl 3BeO, 2SiO3 + A1203, 2SiO3; Euclase

=

=

2

(3BeO, SiO3)+2A1203, SiO3; Phenacite=3BeO, SiO3; Zircon=Zr2O3,SiO3. Hardness=7.5. Beryl and euclase turn milk-white with strong heat and become rounded on the edges; beryl crystallizes in hexagonal prisms, and possesses pretty

distinct basal cleavage, color usually pale-green or emerald-green; euclase crystallizes in clinorhombic prisms and possesses distinct cleavage in two directions at right angles to each other; color pale mountain-green passing into blue and white. Phenacite and zircon do no change before the blow-pipe, excepting that zircon becomes colorless; color red, yellow, or colorless, zircon sometimes brown or gray; phenacite is a little harder (8) than zircon.

Ouvarovite (lime-chrome-garnet) = 3CaO, SiO3+ Cr2O3, SiO3. Infusible. Hardness: = 7.5-8.

Gives with fluxes the chromium reactions

[Table II].

Spinel MgO, A1203 ;

=

Pleonaste (MgO. FeO),

=

Al2O3; Gahnite=(ZnO.MgO), SiO3. Hardness= 7.5-8. Occur almost exclusively in octahedral crystals. Spinel and pleonaste, when pulverized, are soluble in salt of phosphorus; color of spinel red, blue, brownish; of pleonaste black. Gahnite is almost insoluble in salt of phosphorus and borax; color dark-green or black. Kreittonite is a black spinel containing zinc and iron, slightly magnetic before ignition.

Diamond C. Characterized by its hardness, which surpasses that of corundum.

TABLE L.—BEHAVIOR OF THE ALKALINE
BEFORE THE

On Ch alone, and in the
forceps.

The Hydrate fuses, boils,

intumesces, and is finally
absorbed by the Ch. The

Carbonate fuses readily to Fuses with Sd to a homo

1. BARYTA. a transparent glass, which, geneous mass, which is ab

Ba0.

2. STRONTIA. Sro.

3. LIME. CaO.

on cooling, becomes enamel-sorbed by the Ch.

white. In the forceps it

colors the outer flame yel-
lowish-green.

The Hydrate behaves like

hydrate of Baryta. The

Caustic Strontia is insolu

Carbonate fuses only at ble. The Carbonate, mixed
the edges, and swells out with its own volume of Sd,
in arborescent ramifications fuses into a limpid glass,
which emit a brilliant light, which becomes enamel-white
and, when heated with the on cooling. At a greater
RF1, impart to it a reddish heat the mass enters into
tinge; shows after cooling ebullition, and caustic Stron-
alkaline reaction. In the tia is formed, which is ab-
forceps, colors the outer sorbed by the Ch.
flame purple.

Caustic Lime suffers no alteration. The Carbonate loses carbonic acid, becomes whiter and more luminous, and shows after cooling alkaline reaction. In the forceps it colors the outer flame pale-red.

Undergoes no alterations. Carbonate becomes caustic and luminous.

4. MAGNESIA. The MgO.

Insoluble. The Sd passes into the Ch, and leaves the Lime unaltered on its surface.

It behaves like Lime.

5. ALUMINA. A1208.

Not changed.

Forms an infusible compound, with slight intumescence. The excess of Sd is absorbed by the Ch.

It behaves like Lime, but does not which becomes opaque by flaming. crystallize so well.