Boulimie d'or

I hung out in the Riverfell cave, approx 3938,2740 and shard hopped until I had all 10. It will take a little bit, as the nodes are about a 30% drop rate for the quest item.

The best location is high above the Riverfell portal in the hills. Take the portal or head north from the crimson wash portal. Take the steep winding trail into the mountains way up north in the zone. Eventually you'll get to a set of tunnels that go into and back out of the mountains (not so much a cave). These have tons of nodes. The entrance to the first tunnel is 3884, 2708. (the paths leading up will take you straight to that location. This path is also the way you have to go to get to the challenge for part 2 of the world event. (jump through glowing yellow/orange circles from the top to the bottom of the cliffs/waterfalls - the circles used don't have to be new - you can jump through the same circle over and over to complete your 10 hoops-jumped-through).

The method by watchme where you don't loot unless you get the Pépite d'or works great. I found all of mine in a cave located at 3930, 2730. You might have to check a few shards to get them all.