Some years ago vermiculite originating from one particular mine in the United States was found to contain certain levels of asbestos and the mine was shut down
A few pictures to key words and parts of the process: Germination Fully colonised Cake pinning Pins growing Cake ready for harvest Veil breaking Caps ready for spore printing Casing ready for spore printing Spore printing Hyphal knots Primordia Overlay Photos by DreaMaTrix More pictures in the Growlog archive and the Gallery.
If you are a beginner and want to grow just a few mushrooms, then cakes are better for you since the whole process is shorter and bears less chances of failure.
There have been no studies to suggest that any of the chemicals contained within any variety of psilocybin mushroom can cause any type of physical damage in the human's brain. what you are thinking of is not a hole in your brain but the use of indorvines to produce the high the psilocybe produces so when you come off of the high your brain is running a little low on some which produces the sight of a hole in your brain if you get a cat scan.