The Black Rock Ledger pages can be found on Act II, City of Blood quest right outside of the Khasim Outpost's east gate in the Stinging Winds desert in an old pirate ship that is stuck within a pile of sharp, black rocks.
There are total of 6 pages found in the game. These pages have no real uses in game, except for transmuting them in Kanai's Cube. Rumors indicated other uses ever since the appearance of these pages, but none of them proved real.
Known Drop Locations
The image (left), shows four possible drop locations (indicated by the red dot) of the ship and ledger pages. The connecting waypoint is Khasim Outpost waypoint.
There is also a checkpoint right before you get to the upper right location, which means that if you need to reload the game for farming purposes, you won't have to change quest. Just "Leave Game" then "Resume Game" and you'll be back at the checkpoint with a reset game and this makes farming this item much easier.
The image (right), shows what the ship looks like. You will find a "Gravedigger" digging near the partial hull of the ship. He will say, "Be careful... This ship is cursed by demons! We should be safe as long as we don't disturb it..." Several Fallen Lunatics will come up from the ground - one will instantly explode and kill the Gravedigger, the rest will attack you; when he dies, the Gravedigger will randomly drop one of the pages of the ledger.
To find the ledger pages, go through the Khasim Outpost's east gate. There are two locations that the black ship may spawn, both almost immediately outside of the gate. The first is the first couple of rock piles southeast of the gate. The second is directly south of the gate, along the western cliffs of the map.
The spawning of this object is random, so if you are farming, you may need to reload the game a few times (Leave Game -> Resume Game) to find any of the pages. Not only is the spawning of the ship instance random, but the page number that drops in this instance and location random. For instance, one person could get page 8 the first time, while another could get page 23. Additionally, it is possible to get the same page multiple times, even before attaining all six.
"Damn, I always thought that being a first mate would be more exciting. I guess I shouldn't expect much from a mining expedition. Ever since we set off from Kingsport, all I've done is sit out on deck and watch the deckhands argue."
"Haven't been able to get much sleep these past few days. Apparently my sea legs aren't as sturdy as i thought they'd be. I've vomited more times than I can count, and every time Captain Hanso offers me some ale, I have to come up with some excuse to decline."
"After three straight days of this storm, I'm almost convinced that this ship has some sort of curse on it. Each week brings some new trouble that I have to deal with. I'm not sure what will give out first, the ship... Or me."
"Reyes tells me that it was some colossal wave that did the ship in. I was down below when it all happened. Several of us survived the wreck. The rest of them have gone off to try and figure out where the hell we are, as if any of that matters."
"Madness, complete bloody madness. The captain has disappeared into the desert somewhere, and the rest of the survivors are convinced there's some sort of monster after us. I'm starting to think the crewmen that died in the wreck got the easy way out, lucky bastards."
"All the rest of them are dead now... I'm the only one left. Strange deformed creatures attacked the wreck, where most of us were sleeping. I managed to get away safely... but I don't imagine it will be that way for long. I can hear them... Giggling in the shadows, like this is some kind of game."
- First Mate McMahon
Green Hills of Stranglethorn
Any of the pages can be transmuted in Kanai's Cube to get an equivalent page of the Green Hills of Stranglethorn. This is a lore book from World of Warcraft, written by Hemet Nesingwary, and a reference to the real-world book Green Hills of Africa by Ernest Hemingway. Interestingly, the pages in Diablo III include some text that was not in the Warcraft book.
The Green Hills of Stranglethron
For this expedition I have assembled Ajeck Rouack and Sir S. J. Erlgadin, along with my trusted servant, Barnil Stonepot. I fought alongside Ajeck's father's side in many battles in defense of the Alliance. Her father schooled her well in the ways of weaponry, and her skills with a bow make me wonder if there is elven blood running through those veins.
During one such misstep, Erlgadin laid a heavy hand on Barnil's shoulder. Ajeck and I gave a casual glance, assuming the man was simply giving Barnil a much-needed scolding for his carelessness. Erlgadin, however, gestured slowly with his head toward a nearby fallen tree. Gazing back at us were piercing black eyes just above a mouthful of razor sharp fangs.
Both Ajeck and Sir Erlgadin stood poised, guns leveled at the bristling overgrowth at the base of the swaying trees. The midday sun beat heavily upon us. A slowtrickle of perspiration trailed down from Erlgadin's temple as he pulled the pin back. Upon the sound of the click, the thick fauna parted and a large black panther -- a beautiful specimen -- darted out onto the plain.
I had promised the expidition that we would spend the next day hunting panthers, as their furs ar in high demand throughout Azeroth. It only makes sense that such demand should exist with all of the able-bodied hunters, trappers and fur-traders off giving their lives so valiantly in the name of the Alliance.
The hunters were now the hunted. I led the party toward the sea, hoping the shoreline would provide refuge from the Raptors. In our haste we had drifted too far north, to a precariously high elevation. The mistake was made. The fault was mine. We stopped just short of a sheer cliff, the Raptors just a few paces behind.
Later that night we sat quietly around the campfire, knowing our lives had been saved by a bizarre twist of fate. Such are the risks of the big game hunter. We toy with fate by delivering it. Yet each of us, at some point, will face fate's razor sharp teeth. This Dwarf is just glad that moment did not come upon the green hills of Stranglethorn.
- Each page refers to a number found on the television show Lost. Also, the first letter in each of the pages text, if combined, spell out DHARMA; a further reference to Lost. The Black Rock was also a wrecked ship in the said series. In addition, page 8 references "Captain Hanso" and page 16 references "Reyes" (both being characters of Lost, Alvar Hanso and Hugo Reyes). Possibly the black dust storms in the desert may have something to do with the Lost smoke monster.