Chlorophyte Brick

Bricks keep the growth property of the raw ore, so a handful of them seeded across a mud farm converts a far wider area than the same ore would have on its own. Build the farm out of bricks, let it grow, and pull ore off the edges. When you need the material for gear instead, Shimmer converts them back, so nothing is locked away.

The bricks slow the spread of Corruption and Crimson the same way a few other blocks do, which makes them a reasonable lining for a containment tunnel you were going to dig anyway. That is a secondary use, since the ore is expensive, but if a farm happens to sit near a spreading biome you get the barrier for free.