App

To install the appstore app, right-click on your turtle to open the GUI, run pastebin get iXRkjNsG appstore. To install cavern, run appstore get ogwillow cavern.
-- https://turtleappstore.com/u/ogwillow/a/cavern
--This is a simple cavern mining program.
--It only cuts blocks in one lane.
--This can be scaled up by running multiple turtles.

local name_of_program = 'Cavern Miner!'
local fuel_level = turtle.getFuelLevel()

print('\nWelcome to the: ' .. name_of_program .. '\n')
print('Your turtles current fuel level is: \n' .. fuel_level .. '\n')

local fuel_return = math.floor(fuel_level / 4 - 4)

print('You can go: ' .. fuel_return .. ' blocks and still return.\n')
print('How many tiles would you like to go forward?\n')

local function go_forward()
    how_much_go = io.read()
    print('\nRunning!\n')
    for i = 1, how_much_go do 
        while turtle.detect() do
            turtle.dig()
        end
        turtle.forward()
        turtle.digUp()
        turtle.up()
        turtle.digUp()
        turtle.down()
    end 
end
--The code above sends the turtle forward as much as you want (assuming fuel).
local function cut_blocks()
    turtle.dig()
    for i = 1, 2 do
        turtle.up()
        turtle.dig()
    end
    turtle.down()
    turtle.down()
end
--This tells the turtle to cut another three blocks in front of it.
local function dump_crap()
    dont_want = {
        ["minecraft:stone"]=true,
        ["minecraft:dirt"]=true,
        ["minecraft:cobblestone"]=true,
        ["minecraft:andesite"]=true,
        ["minecraft:diorite"]=true,
        ["minecraft:granite"]=true,
        ["minecraft:gravel"]=true,
        ["minecraft:tuff"]=true,
        ["minecraft:cobbled_deepslate"]=true
    }
    --Items we don't want.
    for i = 1, 16 do
        turtle.select(i)
        local dropped_item = turtle.getItemDetail()
        if dropped_item and dont_want[dropped_item.name] then
            turtle.drop()
        end
    end
end
--Items to be dropped.
local function return_turtle()
    for i = 1, how_much_go do
        while turtle.detect() do
             turtle.dig()
        end
       
        turtle.forward()
    end
end

go_forward()
cut_blocks()
dump_crap()
turtle.turnLeft()
turtle.turnLeft()
--Turns turtle around.
return_turtle()
-- Returns turtle.
print('Done!')