A free app for Android, by appspouch.
Gold Metal Detector is a free and easy-to-use tool for detecting and measuring the presence of metals, including gold and silver. The application uses your phone’s built-in magnetic sensor to detect the magnetic field values and turns your Android into a real metal detector to find gold around you.
The app can be used to detect the presence of metals in a variety of different items and materials, including gold and silver jewelry, steel products, copper products, and more.
To use the app, simply open it and start tapping the screen, which will then begin beeping and showing you the results of your test.