From the standpoint of exposure to radioactive minerals, which building material would probably be the most "safe"?

Wood is likely to be considered the safest building material from the standpoint of exposure to radioactive minerals. This is primarily because wood is a naturally occurring material that does not typically contain significant amounts of radioactive elements.

In contrast, granite often contains higher levels of natural radioactivity due to the minerals it includes, such as uranium and thorium. Over time, these radioactive minerals can release radiation, potentially leading to health risks if exposure levels are significant.

Brick and cement can also contain materials derived from sources that may include trace amounts of radioactive minerals, depending on their composition and the sourcing of their raw materials. While they are generally more stable than granite with respect to radioactivity levels, they are still more susceptible than wood, which lacks these concerns entirely.

Thus, considering the nature of each material, wood stands out as the safest choice for minimizing exposure to radioactive minerals.