Mineshaft

down = -1
blacklist = {"minecraft:stone","minecraft:gravel","minecraft:dirt","minecraft:grass","chisel:limestone","chisel:marble",}
mine = true

repeat
    for i = 1,4 do
        sucess, block = turtle.inspect()
        for x = 1,#blacklist do
            if block.name == blacklist[x] then
                mine = false
            end
        end
        if mine == true then
            turtle.dig()
        end
        turtle.turnRight()
        mine = true
    end
    turtle.digDown()
    down = down + 1
    while turtle.attackDown() == true do
        sleep(0.5)
    end
until turtle.down() == false

for i = 1,down do
    while turtle.attackUp() == true do
        sleep(0.5)
    end
    turtle.up()
end