The survival update added a lot of things, but also made ores harder to find.
Where to Find Ores
Since the Survival Update has changed the ore generation significantly on planets, you'll be hard pressed to find anything now. Or are you?
Turns out, all they did was change the way the voxel appears on the surface.
You won't be able to find ores by looking for dark patches anymore. Instead, you should look for subtle, light discoloration in the ground to find ore veins.
In the snow, you might be able to notice yellow spots. This isn't the sunlight, this is the ore patch. It's a lot more obvious when the snow is in the sunlight's shadow, too.
It's still difficult to find these patches just because they're so hard to spot, especially on noisy grass or rock terrain, but you can try scrolling out your view with alt+mousewheel to get a good picture of the terrain, and you might be able to find these patches easier.
But What About Other Spots?
Good question! It seems someone has already published a list of all the different texture variations you can encounter in your quest to find ores.