Tourmaline
a widely-distributed , a widely-distributed being used as gem-stones. Its crystallization, is rhombohedral, hemimorphic; prisms often triangular. Hardness, 7- 7.5; sp. gr. 2.94-3.3; luster, vitreous; colblack the most frequent, but also blue, green , red, often of rich shades, sometimes red internally and shades of green externally. Composition:
Very variable, the oxygen ratio for the protoxide and sesquioxide, and also for varying considerably.
Dana distinguishes the following varieties: (1) ties: (1) Rubellite; shades of red, frequently transparent. (2) Indicolite; of an indigo-blue color. (3) Brazilian sapphire of jewelers; Berlin blue. (4) Braor Peridot); green and transparent. (5) Peridot of Ceylon; honey-yellow. (6) Achroite; colblack. (8) Columnar and black , without cleavage or trace of fibrous texture . A series of analyses and sp. gr. determinations, made by Rammelsberg, has suggested sted the following lowing subdivisions: (1) Magnesia tour- (2) Ironmagnesia tourmaline, mean sp. gr. 3.11; (3) Iron-tourmaline, sp. gr. 3.13-3.25; tourmaline, mean sp. gr. 3.083; (5 ) Lithia tourmaline, mean sp. gr. 3.041. The blowpipe reactions vary with the composition, which is essentially a boro-silicate of protoxide and sesqui-oxide. Occurs in granites, notably the albitic varieties, schists, and dolomite. an TOURNAMENT, tween armed knights on horseback in encounter betime of peace, as time of peace, as an exercise of skill by honorary dis- TOURNAY tinctions), and usually an adjunct of etc. The tournament was one of the most some great event, as a royal marriage, cherished institutions of the Middle Ages, furnishing, as it did , an exciting show, and giving the combatants an opportheir skill, courage and prowess before their friends. The arms employed were usually lances without heads, and with round braces of wood at the extremity, and swords without points and with out points and with blunted edges. Oc- , the ordinary arms of warfare were used, and it not infrequently happened that the tournament ended in a hostile ment ended in a hostile encounter. Cerof birth were required for admission to the tournaments. The place of combat was the lists, a large open space surrounded by a rope or galleries erected around for the spectators, the heralds, and the judges. The tilting armor was with some device of a lady's favor. The of light fabric, and generally adorned prizes were delivered to the successful knights by the queen of beauty, who pointed by the king. had been chosen by the ladies or aptest of skill, in which a number of indi- In modern usage, a competition or concompetition or conviduals take part; as viduals take part; as, military tournanament, etc. ment; cycling tournament; billiard tour-