Song of Sadness
Glow Sand is just what it sounds like, sand that glows. It offers a faint light that lasts for an exceptionally long time, and is often used to mark things such as paths to make them easy to follow in the dark. Pure glow sand has a density of 25lb / cubic ft.
Glow Sand can also be refined and used to craft a Gem of Brightness (DMG pg 171). A single Gem of Brightness can be successfully crafted with 1 lb of Glow Sand, and the appropriate kiln and other equipment.
During peace times, glow sand was bought and sold as a commodity. On Sarlona, the average price was 200gp/lb.
Glow Sand is also a key component in making a Bellanon Pillar, which can be made using 5 lbs of glow sand.
Of particular note, Vaelon Eskeban obtained large amounts of Glow Sand from the mine in Fort Petanth.
The Orc Prince Gamaebar also has a notable supply. However, his castle is located in the Outer Plane of Acheron.