If ore:

Split the ore into 3 layers, aka dublicate it 2 times, take the first one and "cut out" the ore chunks, aka erase all the stone parts, move over to the other layer and darken it by -80, 
then make that layer transparent with just 5. should also be between the 2 layers.

Now start with making one texture, aka the normal one, which should be named s(letter if it's not the first texture) after that, apply the transparent dark layer, name it 50, then make it 5
more transparent, and so on, until you get to 5 and 10, 10 will not be darker, but will have a slight deepslate tint, 5 will be 10 darker, and have a stronger deepslate tint