Richard wants to die, Jack lights dynamite at Black Rock

On their trek across the island, Hurley quizzes Richard asking if he's time traveling, a cyborg or a vampire, to each of which Richard answers no. They then approach the Black Rock instead of the temple and Richard tells them that everyone at the temple was dead, but their friends were not there. He then tells Hurley not to believe anything Jacob told him.

Richard approaches the Black Rock, telling them that he's going inside to die. Once inside, Richard examines some empty chains and tells Jack that he hasn't been back to the Black Rock since he was first there, implying what many have thought, that he was a slave on the ship. He opens a crate of dynamite ignoring Hurley's emphatic warnings and tells them that he can't kill himself because Jacob touched him which was supposed to be a gift, but was really a curse. Richard slams a stick of dynamite down and nothing happens.

Richard says that he devoted his life to Jacob who told him he had a plan which he would one day reveal and that he would be a part of. Now that Jacob's dead, Richard says that his entire life had no purpose and that if someone else lights the fuse, then he can die. Jack lights the fuse but then sticks around for a chat.

Richard tells Jack that he should go or he's going to die, but Jack tells him that he thinks that won't happen. Jack tells him about what he and Hurley experienced at the lighthouse and that Jacob has been watching him since he was a small child. Jack says that if Jacob went to all the trouble to watch him and bring him to the island, that he's not going to let him die there. Jack closes his eyes as the spark approaches the dynamite and then it goes out at the last moment. Jack smiles and asks Richard if he wants to try another stick.

Richard now seems convinced to follow Jack and asks what they should do next. Jack says they'll go back to where they started, which is the beach camp.

So there are a few lofty answers here. We now know what Jacob's touch means and essentially that Richard was a slave on the Black Rock. The touch explains why Michael couldn't kill himself in season 4, but when did Jacob touch him?