Examples from the Web for conchoidal
There is an imperfect cleavage parallel to the basal pinacoid, and the fracture is conchoidal.
Flint breaks with what is called a conchoidal fracture, as do many other substances, such as glass.
The paste is very fine 327 grained, and breaks with a conchoidal fracture.
Bulb of Percussion—a bulb resulting from a conchoidal fracture of stone.Handbook of Alabama Archaeology: Part I Point Types|James W. Cambron
The ware is nearly always well baked and hard, breaking with a saccharoidal, rarely with a conchoidal, fracture.