Crossword puzzle clue "mineral containing magnesium"

a roughly spherical stone, hollow or partially hollow, containing an accumulation of mineral matter

the smallest particle in an element which can take part in a chemical reaction

(Nahuatl) a small evergreen tree of South America and the West Indies, from the fruit of which cocoa and chocolate are prepared

a substance that cannot be separated into simpler substances by chemical means

EM, a unit of measurement in printing