What's wrong with using black marble as a door cover?

From the perspective of chromatics, as long as it passes the radiation angle test, we should know that almost everything we can touch has radiation, including ourselves, as long as the intensity is harmless to the human body.

From the perspective of geomantic omen, we should still consider the size of space, housing pattern, gate orientation and so on. In fact, it is not necessarily impossible.

There may be some opinions about pure superstition. I'm not sure. If the elderly at home say that it is unlucky, we must change it from the perspectives of family harmony, neighborhood relations, filial piety and care for the elderly, or seek the opinions of the elderly to deal with it. Harmony is the most important!