k, so I know you're basically going from no shading to shading here, therefore making a reflective surface specially one that takes as much subtlety as bronze is too much (you just had to go straight to metal didnt ya?) What you have does not look like metal at all, but it's good enough for now I think.
I thought the chrysler building would make it really clear, but you still dont know what I mean by making a design for the furnaces.
look at these, the smallest arches have 3 holes, each hole could be a furnace, then you have an extra hole below and it would look cool.
When you design that furnace shape, you probably want to temporarily eliminate all the shading, and just look at a black sprite with white holes, that way you know you're not being distracted by all the detail.
Your fire is just as bright and saturated as your gold and that will not do. Fire is a lightsource while gold is not, you have to make it lighter somehow.
I went and designed something myself, just white or black holes like this would actually be better than what you have, there is no distinguishing anything that's going on in your chest right now.
see how the fire here is emanating from the opposite source than the light, that creates contrast. You cannot have fire with shades similar to your gold because it'll all blend together. This animated version has a less saturated gold for that purpose.
Also, these have a lot less stuff going on, I pixeled most things iwth a 2x2 brush
Now for the Bronze, the reference posted here was lovely
But trying to achieve that in pixels this small, specially ones meant to be animated is madness. So I just went for the dark metal with red-ish highlights. as I shaded it I was thinking the same way I would've as if it were black metal.
I actually made it before the gold one,gold one is the same with some shades shifted around.
that sillouething light (a secondary lightsource coming from the borders) is a very easy way to achieve that reflective look. But I want to show some other ways it can be done
This is a good, simple example of dark shiny material from Galaxy Fight
This is a metal guy from Waku Waku. This one just has really contrasted highlights right next to the shadows, that is the easiest way to fake metal, going right from lightest highlight (specular) to darkest (core) shadow.
Galaxy Fight and Waku Waku make good starting points for shading, good volume, no overcomplication...as I keep saying over and over :p
This guy is an example by me of that aproach. See his big metal fist? all I did was put a big bold core shadow right next to the higlight and BAM metal.
some more really simpy shaded metal objects by me for Deathroad to Canada
I just had to bring St0ven's brass monkey into the party =)
You should look at proko's shading video for tips on shading https://www.youtube.com/watch?v=V3WmrWUEIJo
and maybe Arne's tutorial http://androidarts.com/art_tut.htm#materials
and if you really want to get deeper on how light works you can look at the "itchy animation" light tutorial http://www.itchy-animation.co.uk/light.htm
After messing with your sprite for a while I felt bad I couldnt really call it my own and made my own take at your idea. I know you probably werent going for tron-lines for furnaces :p
This is my full proces+refference file on this. You'll notice there are several frames that are just black with the white furnaces, that's to make sure I'm focused on getting that right. You should've probably designed the furnaces before you ever started shading