acidic

adjective3

1. •
   Of or relating to acid; having the character of an acid.
2. •
   Having a pH less than 7, or being sour, or having the strength to neutralize alkalis, or turning a litmus paper red.

   • The swampland is an extensive pegasse swamp, which is rich in organic matter and intensely acidic. — 2015
3. •
   Containing a high percentage of silica-bearing minerals.