Natural ore colors are as follows:

• Iron
Red when mined, but then becomes a silver after its processed.
Natural Form: https://www.thermofisher.com/blog/wp-content/uploads/sites/4/2018/08/iron20ore-1.jpg

• Copper
Also red to reddish brown. Copper is not green. It turns green when it oxidizes when in contact with other elements.
Natural Form: https://cdn.shopify.com/s/files/1/0190/1942/products/IMG_0530.jpg?v=1571438507

• Uranium, pure white or silverish white. Green under sunlight, Vibrant green when under UV light.
Natural Form: https://cdn.mos.cms.futurecdn.net/wY8xvoNKAiQd95eWMq2NR6-970-80.jpg

Now, generally how we perceive these elements in game, we see them above ground, but the perception is that they are underground and we use miners to dig "up" the ore. I feel that when the ore is exposed to the elements after pulled out of the ground, that is when the colors should change. But even when ore is processed, their colors change well.

For example:
Copper on the ground: https://prnt.sc/quabl7
Then copper after being mined: https://prnt.sc/quadk3
Then Copper plates after being processed keeping its default model and potentially having some slight discoloration from the oxidization

I'm going to assume that this is a suggestion, not a report of some freaky bug. I mean, these screenshots aren't why it looks for you when my mod is installed, are they?

I don't share your assumption that the ores are implicitly underground. It would be pretty inconsistent with the rest of the game. I'm convinced that the ores are supposed to really be on the surface, as a part of alien geology of this planet.
They are right to be oxidized then. I would maybe agree that the already excavated ore on conveyor belts should be oxidized only on one side so they look like they are separated from a larger whole. I'm not going to make a new texture, though. Graphics isn't one of my strengths and I needed help to make the first version. I won't be able to make anything more complex than the current texture.

Suggestion really