While the French laboured in building the stockades and in hauling provisions and equipments from the ships to the forts, they made other discoveries that impressed them more than the forest wealth of this new land.

Close beside the upper fort they found in the soil a good store of stones which they 'esteemed to be diamonds.' At the foot of the slope along the St Lawrence lay iron deposits, and the sand of the shore needed only, Cartier said, to be put into the furnace to get the iron from it.

At the water's edge they found 'certain leaves of fine gold as thick as a man's nail,' and in the slabs of black slate-stone which ribbed the open glades of the wood there were veins of mineral matter which shone like gold and silver.
Cartier's mineral discoveries have unfortunately not resulted in anything.

We know now that his diamonds, still to be seen about Cap Rouge, are rock crystals.

The gold which he later on showed to Roberval, and which was tested, proved genuine enough, but the quantity of such deposits in the region has proved insignificant.