Bungie recently implemented several changes in the latest patch to Destiny. Among these include patching the "loot cave", which was an area in Skywatch where players could shoot into a small cave opening from a distance, and have enemies constantly respawn out of it. Players used this area to grind for hours, and collect rare gear from the fallen monsters. Bungie commented on the cave as well as other details of the patch
The spawn rate in this area was reduced significantly, meaning it is no longer an effective place to get material. However, after this patch was implemented, a new area to farm loot was found in the Rocketyard area of Old Russia on Earth. PS4Trophies has a video detailing the new loot "cave".