(8) Special reactions. In fine powder moistened with cobalt-solution and heated yields a blue color.
Mineral. Websterite
Formula. [...Al][...S] + 9[.H].
Behavior
(1) in gla.s.s-bulb. Gives off water, and, when heated to incipient redness, sulphurous acid.
(2) in open tube. --
(3) on charcoal. Gives off water and SO^{3}, leaving an infusible ma.s.s.
(4) in forceps. V.
(5) in borax. Behaves as alumina.
(6) in mic. salt. As in borax.
(7) with carb. soda. Yields an infusible ma.s.s, which laid on silver and moistened, produces a black stain.
(8) Special reactions. Fused with pota.s.sa in platinum has no action on silver. Cobalt-solution produces the alumina reaction.
Mineral. Native Alum
Formula. [.R][...S] + [...Al][...S]^{3} + 24[.H].
Behavior
(1) in gla.s.s-bulb. Intumesces greatly and gives off much water.
Strongly heated, evolves SO^{3}, which reddens litmus.
(2) in open tube. --
(3) on charcoal. Intumesces and become infusible.
(4) in forceps. V. Colors the flame violet if a pota.s.sa alum--yellow if soda--be present.
(5) in borax. Dissolves and gives the iron and manganese reaction, if these oxides be present. Otherwise the bead is colorless.
(6) in mic. salt. As in borax.
(7) with carb. soda. The alkali is absorbed into the charcoal, leaving an infusable ma.s.s which gives the sulfur reaction on silver.
(8) Special reactions. If not containing too much iron or manganese gives an alumina reaction with nitrate of of cobalt. In other respects as the preceding.
Mineral. Turquoise
Formula. [...Al=]^{2}[.....P] + 5[.H].
Behavior
(1) in gla.s.s-bulb. Evolves water, occasionally decrepitates and turns black.
(2) in open tube. --
(3) on charcoal. Turns brown, but remains infusible.
(4) in forceps. V. As on charcoal. Colors the outer flame green.
(5) in borax. In the oxidizing flame, gives a green bead, due to copper and iron. In reducing flame, opaque red.
(6) in mic. salt. As in borax.
(7) with carb. soda. Intumesces, then fuses to a semi-clear gla.s.s colored by iron. With more alkali yields an infusible ma.s.s.
(8) Special reactions. Gives the phosphoric-acid reaction.
Mineral. Wavellite
Formula. [Al=]F^{3} + 3([...Al=]^{4}[.....P]^{3} + 18[.H].)
Behavior
(1) in gla.s.s-bulb. Evolves water and some fluorine, which attacks the gla.s.s.
(2) in open tube. --
(3) on charcoal. Exfoliates and turns white.
(4) in forceps. V. As on charcoal. Colors the outer flame green, especially if moistened with SO^{3}.
(5) in borax. As alumina. Generally gives also a slight iron reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Forms an infusible white ma.s.s.