Red sandstone

Red sandstone is the ingredient used to create Robust glass after As a First Resort... and requires 81 Mining to obtain. The only known location to mine Red sandstone is just outside Oo'glog, near the agility shortcut in the wall. Mining this yields 70 experience per block, but players are only able to mine a maximum of 50 Red sandstone daily, which resets at midnight GMT.

Note that even though only 50 can be mined per day, there is no limit to the amount of Robust glass that can be created per day.

Uncut gems and Strange rocks can be received from mining red sandstone. In addition, both the Penance horn and the Sacred clay pickaxe will give bonus experience when mining it.

Shooting Star Bonus
It is possible to mine more than the maximum daily amount with the reward from shooting stars, which gives the player a chance of receiving double ore. Assuming the player is mining all the Red sandstone available, the effect of the reward given by the shooting stars will allow the player to mine around 13 extra pieces per day. The Resourceful aura can also be used to slow the depletion of the rock so that more than 50 can be obtained per day.

Trivia

 * Red Sandstone also alludes to the parallels Oo'glog has with the Australian outback. Most rocks tend be red, and difficult to mine en masse.
 * Red sandstone is gathered almost at the same speed as concentrated gold ore.
 * Varrock armour does not work to get multiple pieces of red sandstone.
 * Juju Mining Potions will bank the red sandstone.
 * Beasts of Burden will hold Red sandstone, even though it is untradable. This is the only known item where this is the case besides extreme potions and overloads.