I have been drawing(trying to) smelter icon for new smelter interface for my "Officially Worst Dungeon Master Mod Ever(it's official now)"(That's actually going to be the name of it. True story). So there it is, my lovely abnomation smelter

furnace 1

I know it looks weird and I would love to fix that. However, I'm not sure what to do with it, thus I ask the great people of the Internet to look down upon this mere mortal and show him the right path.

I am not responsible for any injuries you experience because of the horror of this picture.
Change the shading. I mean, light source is usualy above (if in your game it isnt, just ignore it ;P) in games, so the side part of smelter should be darker than the uper one. Also use examples, look at google how smelters looks like and try to imagine it in the perspective you need. It misses effect of very high temperature, it just look like camp fire inside of some rock-thing. Some glow would do the thing. Its second light source i guess, so the thing is a bit more complicated.. But i believe in you ;P
There are few things I forgot to mention.
First of all, this icon won't appear on the map. It is going to be just a simple decorative icon at the corner of the interface of smelter station. I hope to make something similar to those extra animations of certain buildings in Stronghold Crusader.
Second, I assume the smelter in the picture is placed inside. I mean, the dark place where only actual light source is the smelter itself.
Third, I'm trying to make old type of smelter and I'm having trouble finding anything good, so I have to resort to my imagination.

But you have point about the fire, it really looks too cold for it.Through I'm not sure what I should do about it. maybe I will add glow and see if I have any ideas then. Thanks for feedback!
Well, I threw together a little example of how I think it should look with a glow. You would probably want to shift the pallet a little bit, though.

I don't dig it. It's actually not realistic to use the flame within as a light source to light the outer rocks, and it bothers me a lot. Sure, add a glow, but the highlights all facing the center makes it look almost like the frontal surface is concave.

There's nothing that's especially rocky about the texture, even though that's what it looks like you're trying to achieve. All of the surfaces almost look like they're smoother than a baby's butt, except for the concaving bit in the front.
Here's my quick and dirty edit:
Sorry for no posting for a long time. I was quite busy but I made some progress. Here is the result:
Smelter 2
I know it isn't good, you probably could do better blindfolded, but that's the best I can do. I will still stick with fire as only light source, let's hope background will make front's shadows look better. I tried to add some glow, but I got carried away while drawing. Same thing happened with minor shadows tweaking, but I think it looks better now. I took note of some S4B3R's advice and made rocks rockier, and now they rock(not really, but couldn't resist a pun). I also made back surface smaller, to make it look slightly more dimensional. Well, that's pretty much all I have done. I should probably make bars mould and background now. If you have any more advice, I will gladly use it.
It is better now for sure. But if its ready icon, i would suggest a background. White one never is a good choise, if it doesn't have meaning. Maybe dark one, also with glow, i dont know. Now there is just too much meaningless space :) If you still have 'energy' for that, try to make those rocks bigger, you will have more space to add shades on them and it will just look more clean. I think a size of 3-4 small ones would do the thing, and you still will have and old smelter effect you wanted. But nicer :P There is a fast way to make textures like cliffs etc instead of drawing outline. Just draw everything in one, the darkest color, and then add stones using brighter one. Then shade those rocks with brither/darker. The first color will become your outline, but you will have more control in shaping stones. Its my way of doing stuff like this, i hope its understandable :P
Yes, there will be background, there is simply no way I could keep white background. I think I will draw the smelter placed next to the wall. I will try to make floor and walls look like in the game, for obvious reasons. The floor will have similar texture to the smelter, while the wall will be more brick-like. The background will probably be dark grey(maybe even cold grey), as it's the only stone color(yet) in the game. For short, there will be background and I have it pretty much planned already.

Also, which rocks should be bigger? The ones closer to the center?
Every. Now there is a lot of banding and it doesnt look nice. Its just suggestion, but with bigger one you will be able to have more control here and since its your first steps in pixel-art, it will be a lot easier for you, and effect can be better too.. Now some stones just dont look like stones, just try out my advice. Also, black lines are ugly if you dont use them well, which isnt that simple ;)
It looks a bit pillow shaded now but I dig it. Definitely an improvement over what you had previously.
In response to Martys1103
I think a big problem with this is the lack of depth in the stones. The lower portions of the stones need more darkness and towards a specific side (depending on the light source direction), and a lighter but not lightest color on the opposite side of the stone.

(Cliff tile I made a long time ago).

Your rock: (Left) compared to my edit (Right).

Another example:

Hence the "quick and dirty" edit :P
For the most part, I used his palette and didn't feel like changing the contrast in the palette was worthwhile in the edit to demonstrate what I meant by rockiness.

I find his latest iteration of the sprite to be more relevant than my edit when it comes to giving critique; his latest iteration of the sprite has nearly as much contrast as what you're trying to encourage.

In the context of what this is supposed to be, the style of shading and contrast in your example is not exactly appropriate for a man-made structure. It's too rocky.

An example of a man-made stone structure. Notice how the surface is rocky but relatively flat and along a plane. When any individual rock juts too far out of the surface, it becomes easier to remove and compromises the strength of the wall in the structure.

With the shading style that you're encouraging for this, it seems like each individual rock is not very tightly packed because of how far each rock extrudes.

Don't take this the wrong way; I like your additions to the palette and your style of shading rocks (though I don't agree with your cliffs, but that's on a tangent).
After one month of not updating, I finally updated the icon. Before I back down from posting, I will post the picture right this very moment:
Smelter 3
The first thing you probably notice is the mirror on the floor. That's supposed to be floor, but floor is a troll and refused not being a mirror, thus I had to give up.
Also, I have broken any sane limits of colours in any kind of pixel art. It's freaking single-colour rainbow.
But I don't know what to do with the wall in the background. It looks too plain, but I have no idea how to make it look more interesting.
Oh, I nearly forgot. Egor, I used your advice about textures("like cliffs") and it was really great. I really had more control over shape. It was weird at first, but it turned out nice, I think.