Originally Posted by: pizzicatopickerUnder the idea the chords of a specific key are derived from the formula 1,4 and 5, does that make them ALL minor?[/QUOTE]
The standard triad chords for a key are derived from building a chord containing a 1st, 3rd & 5th relationship on every note of a scale using only notes from that scale.
[QUOTE=pizzicatopicker]Like, the Key of C, just for simplicity... Cm, Fm, Gm?

Right.

But of course you can alter the scale in order to get different chords. This is the reason the harmonic minor scale exists. In order to get a major V chord (with a good leading tone!) - in C minor this results in a G major chord (or any G with a major 3rd, like G7) you need to have the major 7th degree - in C minor a B natural, instead of a B flat. And melodic minor also raises the 6th degree so you get an A instead of A flat and therefore a major IV chord.

Hope this helps.