or bent and aggregated in rosettes. The colour is dark grey or green; a
characteristic feature is the pleochroism, the pleochroic colours
varying from yellowish-green to indigo-blue. Hardness, 6-1/2; specific
gravity, 3.4-3.6. It occurs as isolated scales scattered through
schistose rocks and phyllites of dynamo-metamorphic origin. The
ottrelites of the phyllites and ottrelite-schists of Ottrez and other
localities in the Belgian Ardennes is a manganiferous variety of
chloritoid, but owing to enclosed impurities the analyses differ widely
from those of typical chloritoid. (L. J. S.)

CLISSON, OLIVIER DE (1336-1407), French soldier, was the son of the
Olivier de Clisson who was put to death in 1343 on the suspicion of
having wished to give up Nantes to the English. He was brought up in
England, where his mother, Jeanne de Belleville, had married her second
husband. On his return to Brittany he took arms on the side of de
Montfort, distinguishing himself at the battle of Auray (1364), but in
consequence of differences with Duke John IV. went over to the side of
Blois. In 1370 he joined Bertrand du Guesclin, who had lately become
constable of France, and followed him in all his campaigns against the
English. On the death of du Guesclin Clisson received the constable's
sword (1380). He fought with the citizens of Ghent, defeating them at
Roosebek (1382), later on commanded the army in Poitou and Flanders
(1389), and made an unsuccessful attempt to invade England. On his
return to Paris, in 1392, an attempt was made to assassinate him by
Pierre de Craon, at the instigation of John IV. of Brittany. In order to
punish the latter, Charles VI., accompanied by the constable, marched on
Brittany, but it was on this expedition that the king was seized with
madness. The uncles of Charles VI. took proceedings against Clisson, so
that he had to take refuge in Brittany. He was reconciled with John IV.,
and after the duke's death, in 1399, he became protector of the duchy,
and guardian of the young princes. He had gathered vast wealth before
his death on the 23rd of April 1407.

CLISSON, a town of western France, in the department of
Loire-Inferieure, prettily situated at the confluence of the Sevre
Nantaise and the Moine 17 m. S.E. of Nantes by rail. Pop. (1906) 2244.
The town gave its name to the celebrated family of Clisson, of which the
most famous member was Olivier de Clisson. It has the imposing ruins of
their s