go to the snow island at 30 lat, 10 lon. There are tons of trilobites which drop silica pearls and black pearls. white and blue rocks in the water (not the white and black oil rocks) can also give you silica pearls. you also need silica pearls for yuty saddles for bosses. Hoped this helped!
On Crystal Isles, at about 42 40 there is a little white lake. There is a waterfall in the lake, and on either sides close to the waterfall are around 1000 silica pearls, + the ones in the beaver dams. Just be careful because in my case there was a Yuty pretty close by.