This cache is a simple 2-stage Multi. Go to the posted coordinates. What material are you standing on? Enter that word into Certitude. This is a keyword solution. The final is a short distance from the posted coordinates.
You can validate your puzzle solution with
certitude.
*** This cache is part of the Geocachers of the Bay Area (GBA) Cachin' the Bay 2025 Passport Series. Completed passports are no longer being accepted, since the Block Party is over, but the caches in the series will remain active for people to find! ***