Similar to Chromite, Nightstar Sand is an item that cannot be crafted and will need to be found on the Feybreak Island. Nightstar Sand is used in many different recipes to craft advanced tools in the Feybreak update. This item is not as intuitive to find or create as other items in the game, so make sure to read this article closely to understand how and where to get Nightstar Sand.
Once night time has fallen, go to any sandy place on the Feybreak Island and look for glowing spots on the ground. This is Nightstar Sand. Interact with them to gather the sand.
One of the best spots to grind the sand is in the northeast part of Feybreak Island. Specifically there is an area called Scored Ashland that is a huge open area of sand. Come here at night to find plenty of Nightstar sand quickly, however do watch out for the high level Pals in the area.
Another location to find the sand is near the Tower of PIDF, in the Dessicated Desert on the northeast side of the full island.