The factory type building found in altis, specifically at 053179, has a graphical bug when you try to blow it up When it shifts from the fresh texture to the damaged texture (not to be confused with the destroyed model/texture) the metal parts, like the roof and doors turn purple.

I noticed when trying to destroy it satchels. It took 5 to change to purple and 8 to destroy (seems excessive, but thats another ticket).