Nonetheless, large amounts of asphalt occur in concentrated form in nature.
Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things.
From the Greek, the word passed into late Latin, and thence into French (asphalte) and English ("asphaltum" and "asphalt").
In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the "asphaltic concrete" used to pave roads.
In American English, "asphalt" (or "asphalt cement") is commonly used for a refined residue from the distillation process of selected crude oils.