suspicious rocks

I like the concept of suspicious sand and gravel, and I want to expand that idea to other blocks. Suspicious red sand is an easy candidate, but what about rock blocks that can't be brushed? How could that work and be useful?

Introducing any other suspicious blocks would help the feature feel present and accessible to players, and there a lot of rocks in minecraft. If suspicious rocks occasionally formed somewhere above or near the end of an ore vein, following these geological trail clues could help guide miners along the trail of an ore vein without increasing the payout too drastically. The drops could be the gems, ores, or dusts related to the vein, with a 0 -3 drop quantity. This could benefit rare ores a lot by being surrounded by suspicious rocks or gravel.