15 ppb is 0.015 grams per tonne gold. 1000 ppb (1 ppm) is 1 gram per tonne.
-----------------------Zend\Session\Storage\SessionArrayStorage Object ( ) -----------------------
-----------------------Array ( [__ZF] => Array ( [_REQUEST_ACCESS_TIME] => 1727692102.942 [_VALID] => Array ( [Zend\Session\Validator\Id] => hh8oogc144sqngjhv68l8ans9t ) ) ) -----------------------