AUduke is right. The CZ5 is not designed for nuggets. It is a coin/jewelry/relic machine. Sure it could pick up a pea-sized nugget, but most nuggets found in nature are pinhead sized, or grain-of-rice sized at largest. Pea and fingernail sized nuggets in nature are VERY rare. If gold-in-its-natural-state is your goal, get a dedicated nugget machine.
And as ironic as it sounds, you may *think* that a dedicated nugget machine, designed to be seeeooo sensitive that you can fine teensy things like that to respectable depths, would/should make it a great coin machine, right? (afterall, you won't miss ANYTHING, right?). But the opposite is the case. You would go crazy going to the average urban site (park, lawn, demolition site, ruins site, etc...) because every single pinhead, bread-tie-twisty, birdshot, staple, etc... would be blowing your ear-drums off