Two fields control how often you actually see an ore: frequency and size. Understanding the difference lets you tune spawn rates without breaking world generation.

Frequency vs. size

frequency is the number of placement attempts the game makes per chunk. Raising it means more separate veins appear; lowering it means fewer. size is how many blocks a single vein contains, and variation adds random spread to that size. If you want an ore to be rare but still form decent clusters, lower frequency and leave size alone. If you want lots of tiny scattered pockets, raise frequency and lower size.

Adjusting safely

Open the relevant JSON in orespawn and find the ore's object. Change frequency up or down in small steps and test in a fresh chunk — existing chunks keep the ores they already generated, so you must explore new terrain to see the difference. Keep min_height and max_height sensible; an ore confined to a thin band will look rare even at high frequency. Avoid extreme values, since very high frequency across a wide height range can noticeably slow chunk generation. Save and reload after each change.