Instructions
Press "Right" on the directional pad to examine the toolbox with your Techno-Tool. Slide the yellow and blue blocks in the lockpicking mini-game until you can move the lockpick into the slot on the right side of the screen. This will open the toolbox.
Examine the open toolbox with the "A" button. You will see the hammer, but will not be able to tell what kind of metal it is.
Go back to the house and enter the library upstairs to the left. Move the cursor over the book on top of the bookshelf and press "A" to examine it. It will provide you with the information you need to analyze the hammer.
Return to the toolbox in the swamp and press "Up" on the directional pad to equip your Detector. Press "A" to analyze the hammer and learn it is made from solid silver.