Question

insert one comma to separate the coordinate adjectives. volcanic ash, which has an abrasive sandy texture, can include various identifiable particles: crystals, minerals, bits of pumice, shards of volcanic glass, and miscellaneous rock fragments.

Explanation:

Coordinate adjectives are adjectives that modify a noun equally and can be joined by 'and'. In the phrase "abrasive sandy texture", 'abrasive' and'sandy' are coordinate adjectives. A comma should be inserted between them.

Answer:

Volcanic ash, which has an abrasive, sandy texture, can include various identifiable particles: crystals, minerals, bits of pumice, shards of volcanic glass, and miscellaneous rock fragments.