Cinders are fragments of cooled pyroclastic material lava, typically red or black in color.

The following geologic characteristics define a cinder:

• Uncemented.
• Vitric .
• Bubble-like cavities, called vesicles.
• Fragments are more than 2.0 mm in at least one dimension.
• Apparent specific gravity between 1.0 and 2.0 mm.