Malga Mine is where Rolent gets most of its sepith from, esmelas in particular, to use as export goods.
In S.1202, a large piece of septium ore was discovered. In one of their jobs for Cassius, Estelle and Joshua Bright had to go there to retrieve it and then give to Mayor Klaus. While they were there, there was a cave-in and a den of monsters was revealed. Estelle and Joshua worked fast to rescue the workers and managed to make their escape. They then gave the Septium Crystal to the mayor for safe keeping. It is later revealed that Kyle Capua was responsible for the cave-in.
Later on, the Septium Crystal was stolen, but it was retrieved. It was then refined and decorated, and gifted to Queen Alicia von Auslese for her birthday as a present from the people of Rolent. Mine Chief Gaton later reveals to Estelle that the hole has since been blocked up.