Crossword Genius

Regularly mined boron rocks that create pigment (5)

Ross

I believe the answer is:

ochre

'pigment' is the definition.
(ochre is a kind of pigment)

I don't understand how the rest of the clue works.

(Other definitions for ochre that I've seen before include "Light yellow-brown colour" , "What gives a yellow colour" , "Yellow-orange hue" , "Orange-yellow colour" , "Yellow/brown/red pigment" .)

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