For some reason I can't get Thorium to spawn. Started a fresh game with default settings and explored the map via

local radius=2000
game.player.force.chart(game.player.surface, {{game.player.position.x-radius, game.player.position.y-radius}, {game.player.position.x+radius, game.player.position.y+radius}})

but nothing found. Is it so rare or is there a spawn bug?

Hi!

I've tested on experimental factorio version 2.0.70 (+Space Age) and all is fine...
Can you provide more info about your current setup (maybe save file + factorio version)?

The current resource settings: https://github.com/ldinc/apm-mods/blob/6a7ed92bf318714e87b51702a5753958e2ce2cc3/apm_nuclear/prototypes/main/entities/thorium.lua#L122

Yeap, it's rare, and with default settings I got it in radius ~3k (have tested 3 times only)

The screenshot with high density settings for thorium ores (maximum frequency enabled):
https://drive.google.com/file/d/15FeWZFbbLiD-VEhryaGcg_EwNT_R5mBo/view?usp=sharing