Basa needs blastpowder soil to make new fireworks, but he's too busy designing the new fireworks, so you offer to help.
Where to Start the Quest
You can start this quest after you complete the quest The Rift on Eldin Volcano. Go into Goron City and go up a ramp, then go into the northeast door and talk to Basa to start the quest.
How to Complete the Quest
Warp to the waypoint on Eldin Mountain that is next to the Rock-Roast Quarry. If you forgot to add that waypoint to your map, follow the instructions on the Goron City page to get there. Then go west from the entrance to Goron City and check on the sparkle.
Warp back to Goron City and talk to Basa. There will be a cutscene.
Quest Reward
You get 50 rupees for completing the quest. In addition, you can learn the firework echo from the shimmering firework in Basa's room. If you started the quest Explosions Galore! you can visit Dampé to continue the quest.