How do I insert my own texture into a model?

I decided to create a new type of resource in my map (mythril). It should look like gold, but be silver in color. I tried to extract the gold texture from the game's resources and edited the color. I copied all the files (Model), (Material), and (Texture) into the map's folder under new names, because the map should be a local mod (i.e., it shouldn't affect other maps). In all these files, I configured the links down to the image. I inserted the texture similarly to a PWL image, but my resource turned out to be pixelated. I ask for help from those who have some experience in creating graphical mods.