Black Tips on Phiaus Thankerville

[NYCorchidman]

No, fertilizer burn ( not necessarily the same as mineral damage as it sounds too general) shows up from the tip.

Philip- The fact that certain plants are coming from area rich in limestone does not mean they are adapted to high salt content, nor higher pH.
Limestone does not melt like sugar in water.
Many paphs in that same region grow mainly on rock that are limestone with some moss or dirt, and often roots directly touching the rock itself.
However, these plants do not tolerate high salt content in the root zone. Also, pH is not that high at all.