[@BBeast][@Antarctic Termite] He's right.

To an extent. It's all about dosage. If you enter or get close to one of those forests and you take a deep breath full of the air heavy with spores, you ain't leaving. Mostly because your lungs will be shredded from the microscopic crystal spores. But your body will be converted within a day. If you make some slight contact, or minimal exposure... it could take months or years to succumb. It would start at your extremeties, and then the crystal would slowly spread throughout your body...

Plants are a diffirent story. Plants that come into contact with the spores take a few weeks to fully convert, see the above for flora for how this process to occur, and it would then produce its own spores and infect everything else around it. Within two months you could turn an entire forest into crystal from one shrub, and starting the process over in a dozen spots hundreds of miles away.