According to the mod-lore of Taurethrim, their people used gold to build buildings and craft weapons. Their ancient pyramids have a small chance to be in gold, their ancient armours hidden in pyramids are made of gold too. Imagine the amount of gold needed to make these. It's represented in the mod by the high spawnrate of the gold in jungle underground, most importantly in jungle mountains, compared to the other biomes.
But hey! To extract this colossal amount of gold, ancient Taurethrim would certainly have dug tunnels and mines in the mountains to find gold in high quantity.
So I'm said to myself: why to not add old Taurethrim mineshaft or abandonned tunnels in jungle mountains with obvious loots, occasionnal scorpions jungle spawner and all? For the lore's sake!