This is a loose knit medium to bulky weight hat that fits most sizes.  The knit stitch makes it stretchy and adjustable.  The plain green is Corriedale wool.  The yellow ochre is suri alpaca, which is an especially soft alpaca that looks quite a bit like mohair.  There are also bits of silk, mohair and novelty fiber spun in.  There's a round dark burgundy nubbin crocheted onto the plain green top section of the hat.  It can be seen in the first photo above if you look closely.  Sorry for the poor photo quality.  I'm having camera problems which I hope will be resolved shortly.  I think you can see this is one very cute hat, though!