( 161 ) 
ON THE 
FLEXIBILITY 
OF 
ALL MINERAL SUBSTANCES ; 
AND THE CAUSE OF 
CREEPS AND SEATS IN OLD COAL MINES. 
BY 
MR. JOHN B. LONGMIRE. 
COMMUNICATED BY DR. HOLME. 
(Read Feb. 9th, 1816.) 
I Tis well known, that a few mineral substan- 
ces can be easily bent by the hands, and that 
they have, in consequence, been called flex- 
ible minerals. All minerals possessing this 
property are laminated, and those which have 
the greatest degree of flexibility, can be se- 
parated into the thinnest lamina: thus mica 
and tale are some of the most flexible bodies, 
and are very finely laminated. 
Only a few minerals are flexible in hand 
specimens, butmany do, and probably all will 
bend, when acted on in large tabular masses. 
The bending of strata is very familiar to 
VOL, III. x 
