What's the difference between scoria and scoriac?

Scoria

Definition:

• (n.) The recrement of metals in fusion, or the slag rejected after the reduction of metallic ores; dross.
• (n.) Cellular slaggy lava; volcanic cinders.

Example Sentences:

• (1) Scoria (volcanic cinder) was most effective in excluding roots of crested wheatgrass and streambank wheatgrass.

Scoriac

Definition:

• (a.) Scoriaceous.

Example Sentences: