Jeffrey Appling GJG (GIA) Over the mountain and west of Big Sur is the Arroyo Seco river. I do not know of any documented Jadeite or Nephrite Jade in Arroyo Seco so I will share my findings. When I first picked up some iron stained boulders from the river, I thought they were Jadeite Jade. … More Arroyo Seco California. River Jade.