A scale thrown off in forging metal.
The slag of a furnace, or scoriaceous lava from a volcano.
A fragment of volcanic ejecta from 0.5 to 2.5 cm in diameter.
Uncemented, glassy, vesicular (holes created by escaping gas bubbles), pyroclastic material. Cinder can be thought of as "volcanic froth".
Fragment of lava or rock about 1 cm (fraction of an inch) in diameter.
a small piece of material thrown from a volcano during an eruption.
A bubbly (vesicular) volcanic rock fragment that forms when molten, gas-filled lava is thrown into the air, then solidifies as it falls. more details...
A cinder is a fragment of cooled pyroclastic material (lava or magma). Cinders are either intrusive igneous (magma cooled inside the earth) or extrusive igneous (lava cooled outside of the earth). Cinders are similar to pumice, which has so many cavities and is such low-density that it can float on water.