Calcite blocks generate on surface with no amethyst geode nearby

Calcite blocks generate on the surface of the mountain with no geode nearby.

Expected result-

Calcite blocks should generate below the surface and in an amethyst geode.

Actual result-

Calcite is generating too above.

Seed-

947699010

How to reproduce-

1. Create a new world on the seed given above.
2. Go right towards the mountain and there will be a few patches of clacite on the surface.

This bug will cause unnecessary calcite generating on surface.