.21. tests sites A
There are 42("In the beginning, the Universe was created. This has made a lot of people very angry and had been widely regarded as a bad move.") mountain tiles. Let's sample 20% of this, roughly 8.4 tiles.
A.1 New world gen, new seed. 20 minimum volcanism and 5 minimum volcanoes, strangely, didn't saw one. Small region. 2500 scarcity, 3x3, 2 biomes, shallow and deep metals, prevalently mountains.
GREEN TOURMALINE : 21
YELLOW ZIRCON : 106
MORION : 518
CASSITERITE : 628
CLEAR GARNET : 720
PINK JADE : 869
GREEN ZIRCON : 1104
RED ZIRCON : 1208
RAW_ADAMANTINE : 1261
CRYSTAL_ROCK : 3184
HEMATITE : 9025 - Iron Ore
SLADE : 26597
A.2 Same as above, different site, mountain biome, deep metals+flux stone only.
ONYX : 485
RAW_ADAMANTINE : 565
INDIGO TOURMALINE : 836
CRYSTAL_ROCK : 1161
PINK TOURMALINE : 2237
CLEAR GARNET : 2297
TETRAHEDRITE : 6913
SLADE : 52729
A.3 Same as above, different site, mountain biome, deep, shallow metals+flux stone.
MORION : 4
JASPER OPAL : 53
PYRITE : 211
PIPE OPAL : 343
RAW_ADAMANTINE : 384
RED TOURMALINE : 429
RUBICELLE : 516
SPINEL_PURPLE : 602
VIOLET SPESSARTINE : 718
CITRINE : 1199
OPAL_CRYSTAL : 1289
PINK GARNET : 2033
GALENA : 9625
NATIVE_SILVER : 11539
SLADE : 17984
A.4 Same as above, plus aquifer.
CITRINE : 112
RUBICELLE : 180
YELLOW GROSSULAR : 232
PINK TOURMALINE : 522
YELLOW SPESSARTINE : 924
HORNBLENDE : 1505
PRASE OPAL : 1678
BROWN ZIRCON : 1788
TETRAHEDRITE : 4852
MICA : 15077
LIMONITE : 15951 - Iron Ore
KAOLINITE : 41291
SLADE : 51814
A.5 Same as above, no aquifer no flux. Strange. Embark show an aquifer warning but DON'T list one aquifer. bug? Dug until the first cavern and no aquifer. Bug.
Maximal regionoffset seen: 0.
AQUAMARINE : 6
JASPER OPAL : 12
PYROLUSITE : 30
MORION : 52
OPAL_PFIRE : 55
WAX OPAL : 82
ONYX OPAL : 89
CLEAR TOURMALINE : 99
PIPE OPAL : 225
RED GROSSULAR : 246
MILK QUARTZ : 277
RAW_ADAMANTINE : 282
CLEAR GARNET : 307
RUBICELLE : 338
RED TOURMALINE : 368
GOLDEN BERYL : 401
VIOLET SPESSARTINE : 453
JELLY OPAL : 455
LAVENDER JADE : 512
OPAL_CRYSTAL : 755
SPINEL_PURPLE : 757
CITRINE : 859
PYRITE : 1238
PINK GARNET : 1913
COAL_BITUMINOUS : 3151
GALENA : 6392
NATIVE_SILVER : 11476
SLADE : 13847
A.6 Same as above. no aquifer no flux.
Maximal regionoffset seen: 0.
GREEN TOURMALINE : 26
CLEAR GARNET : 267
GREEN ZIRCON : 426
CASSITERITE : 624
RAW_ADAMANTINE : 741
PINK JADE : 870
CRYSTAL_ROCK : 2466
HEMATITE : 9052 - Iron Ore
SLADE : 80649
A.7 Deep metal + flux
Results don't show any metal. There definitively a bug with the embark screen that reports deep metal when there are none.
Maximal regionoffset seen: 0.
PRASE : 245
RAW_ADAMANTINE : 379
RED PYROPE : 388
MOONSTONE : 1079
PINK TOURMALINE : 1176
TOPAZOLITE : 1297
PYRITE : 1629
GREEN TOURMALINE : 2561
SLADE : 15556
ORTHOCLASE : 45835
A.8 Shallow, deepmetals + flux.
GREEN TOURMALINE : 20
CLEAR GARNET : 606
CASSITERITE : 641
PINK JADE : 807
GREEN ZIRCON : 865
CRYSTAL_ROCK : 2961
HEMATITE : 8258 - Iron Ore
SLADE : 62465
A.9 Deep + Flux
Maximal regionoffset seen: 0.
ONYX : 435
RAW_ADAMANTINE : 851
CLEAR GARNET : 1404
CRYSTAL_ROCK : 1555
PINK TOURMALINE : 2216
TETRAHEDRITE : 9061
SLADE : 73536
Results:
From 9 samples, 4 contained Iron ores, 3 tetra, 2 galena and silver(always appearing together), and 1 coal and one contained nothing, despite the embark saying there was metal. This gives you roughly a 44.4% chance of getting iron in a mountainous biome, varying from 8k of hematite to 15k of limonite, so a 11.5k average. 33.3% chance of getting tetra, and thus copper, varying from 4k to 9k, 6.5k in average.
The test was made on all the mountains in the map, roughly a cluster of it. As said, consisted of 42 tiles.
The results shows that geological layers are not being respected, as hematite is from a sedimentary layer and limonite is from a igneous extrusive. They shouldn't appear in the same "biome".
As for iron, it seems you have more chance of getting it in a mountain, as I never saw one in a different biome. I could be wrong, that's just my opinion. This needs more testing.
Despite the failing in understanding the Mineral Occurrence Setting behavior, it seems we can take some conclusion from biome. Further research is needed, though.