Obsidiminer

-- Place down and detect block below

TR = true
TL = false
check_one = false
check_two = false

-- Detect block below
success, data = turtle.inspectDown()

while success do
-- If block is obsidian break and move forward
    if data.name == "minecraft:obsidian" then
        turtle.digDown()
        turtle.forward()
        check_one = false
        check_two = false
    else
        turtle.back()
        check_one = true
-- If not obsidian, turn right and search for obsidian
        if TR then
            turtle.turnRight()
            turtle.forward()
            turtle.turnRight()
            TR = false
            TL = true
-- If not obsidian, turn left and search for obsidian
        elseif TL then
            turtle.turnLeft()
            turtle.forward()
            turtle.turnLeft()
            TR = true
            TL = false
        end

        success, data = turtle.inspectDown()
        if success and data.name ~= "minecraft:obsidian" then
            check_two = true
        end

        if check_one and check_two then
            turtle.down()
            turtle.turnRight()
            turtle.turnRight()
            if TR then
                TR = false
                TL = true
            elseif TL then
                TR = true
                TL = false
            end
        end
    end
    success, data = turtle.inspectDown()
    if success ~= true then
        break
    end
end