Question regarding Blender / Unity object mesh structure

Hey there! Sorry if this is not the right place to ask this, but I wasn't really sure where to ask for this advice since it pertains to both Unity and Blender. If this isn't a good place to ask some direction would be great!

Anyway, I'm making an ore model for my game in Blender and I am a complete beginner to 3D modeling / texturing. I've found it a lot easier to create this model using 2 different objects / meshes in Blender so that I could texture each individually (as opposed to making 1 object and 1 texture and UV unwrapping them just right which is really hard for me right now).

So here is a picture:



So the orange part is the ore, but that is its own object with its own texture and its own UV unwrap. I parented it to the rock object but I didn't merge them together.

So I guess my question is: is this a really bad practice for Unity? I worry that it could really impact performance or something to have these different meshes sitting on one object with multiple textures rather than just using a single mesh with a well made UV unwrap.

Obviously this is a super simple model, but I worry as they get more complex and have more parts.

Thanks a bunch in advance!