That crucifix was probably on a fairly heavy chain (based on the size of the bail). You might go back and hunt around for the chain! Chains are harder to find as detectors are only sensitive to the size of the links, so you'll want to maximize your sensitivity. I once found a medallion that was 10k and the size of a dime. Fortunately for me, it was still on the chain which was 18k and contains over 1/4 oz of pure gold. When I took the medallion off the chain, my detector wouldn't even find the chain.