Ep. 4: Ruri uses magnetism to accelerate sapphire source analysis while Yoko studies fluorites.
Aired on July 27, 2025
Ruri searches for sapphires by analyzing river sand, which Nagi explains recapitulates the geology of upstream drainages. The standard method involves examining sand from each tributary and recording results under a binocular microscope, a process requiring hours of work. To save time, Ruri discovers a shortcut by running a magnet over the sample to remove the magnetic fraction. Meanwhile, Yoko focuses on her fluorites, which may contain tungsten. As Ruri dedicates her efforts to this geological investigation, her friends begin to wonder how she is spending her free time.
Episodes
- Ep. 1 · Ruri seeks affordable quartz and learns geology with Nagi's help
- Ep. 2 · Ruri Prospects for Gold and Discovers the Difference Between Cash and Scientific Value
- Ep. 3 · Nagi and Ruri explore a university lab and discover a mysterious bismuth crystal alongside an old map.
- Ep. 4 · Ruri uses magnetism to accelerate sapphire source analysis while Yoko studies fluorites.
- Ep. 5 · Ruri, Yoko, and Nagi explore a gravel beach for rocks and minerals.
- Ep. 6 · Ruri and friends locate the sapphire deposit after correcting a note error near a shrine.
- Ep. 7 · Shoko finds friends while exploring sea glass and silica color science with Ruri.
- Ep. 8 · Shoko and Ruri investigate water quality and discover orange crystals at an abandoned factory.