Ann: Mt Alexander - Drilling Update, page-88

Hello Jordan,

Just transpose your understanding of what you read and you will not be confused. In that, Mafic refers to the components forming the rock Ma the first two letters for magnesium and Fic the first and last two letters from the adjective Ferric. MAFIC ROCKS therefore contain more iron, they are dark in colour. being iron rich, and can therefore be magnetic and detectable as magnetic anomolies.
the next class are the Ultramafic rocks.

Felsic on the other hand refers to the name derived from the first 3 letters from the word Feldspar (Spar of the field) the first two letters and second last letters in the name silica. Both these minerals are poor non ferrous in their composition, are non conductive electrically and together with micas, are the principal components to form acid (granites, rhyolites and others) and some intermediate rocks (rocks between felsic and mafic), these include dacite and andesite and can form dykes within the mafic intrusives if they come up from the magmatic soup below. Felsic rocks are light coloured and poor conductors electrically.

I will stop there as i don't want to get into a petrology lecture and hope this answers your confusion.

take care and enjoy the ride.

Helmenesh