The game is still bugged in the 1.1 patch - better but not fixed. Achievements are no longer unobtainable but the game will degrade over time. Initially after install it'll work fine but after couple hours of playing power cycling the phone just before playing is required. After a few more hours the time to load just gets progressively longer until it won't load at all. I'm now taking the approach of finishing a campaign mission and the associated collectibles achievement then doing an uninstall/reinstall. Uninstall/reinstall loses your current save and all museum progress (i.e. all progress towards achievements that haven't popped yet).
This is a 3 part mission with no time limit. Part 1 is to collect 20 scarabs. Part 2 is to collect a single tablet. Part 3 is to collect 4 pieces of the mummy's remains.
The usual loop of dig, collect, surface, sell, upgrade/refuel/resupply will get you all the items you need. I was just shy of 2000m by the time I finished.
When you talk to the farmer after finding the 5th mummy piece the mission ends. So, if you want to complete Egyptologist (find all the Egyptian artifacts) don't talk to him until you're ready.
Your tractor has built-in detector with a short range that detects all the needed items (yellow arrow indicating direction of item that gets more opaque as you get closer). You can buy a loot detector with a longer 240m range for $1000 that shows a white arrow but it only lasts about 30 seconds.