Because the story indicated by the Mithril Cube suggests that the gold mine is likely near this ancient Night Shrine, and the gold ore Shard found downstream indicates that the mine is very close to the upper river. Therefore, the two left the cliff and meticulously searched the surrounding area.
Neither of them possessed the specific Arcane Techniques for exploring mineral deposits, such as "Ore Perception"—where land with deposits turns red with a small chance, but if one doesn't deeply understand the technique, there's a high chance of error; "Treasure Exploration"—where treasures in boxes, land, and cabinets show white glimmers, but be cautious these treasures might already have owners; "Money Mouse's Sense of Smell"—which greatly enhances perception of wealth, but the deeper the mastery, the more one dislikes cats.
Fortunately, as a witch holding the position of "Earth," Miss Benanis had a tremendous ability to perceive the earth.
