The Spanish treasure fleet as such operated until 1790. Pure graphite pencils had existed since 1560, but clay and graphite pencils didn’t exist before 1795 (invented by Nicolas-Jacques Conté). The Spanish Empire continued to operate a trade route between the Philippines/Spanish East Indies and Mexico until 1815 though.
Looking at the pictures you posted on your other thread (reproduced below) where you claim the rock has “
numerous Spanish markings” and say “
I don’t think there is any doubt it is real”, I’m afraid I would have to disagree. I see an ordinary conglomerate rock with no apparent evidence of microfossils, nor a treasure map.
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https://www.treasurenet.com/threads/rock-treasure-map.721110/