I usually drop Mineral scarcity down into the 500-1200 range.
The world I'm currently embarking on was generated at 500, & below is the "prospect hell" result from my newest site (immediately after Embark/Initial Save).
Base materials:
SOIL : 68003
STONE : 874489
FEATURE : 30114
MINERAL : 231147
MAGMA : 327736
Liquids:
Layer materials:
FIRE_CLAY : 6606 Z: 102
SILTY_CLAY : 6699 Z: 101
SAND_WHITE : 41524 Z: 100..102
CLAY_LOAM : 6699 Z: 100
SILTY_CLAY_LOAM : 6475 Z: 99
CHERT : 58475 Z: 93..100
SHALE : 30528 Z: 92..98
QUARTZITE : 68484 Z: 50..91
GNEISS : 112981 Z: 58..82
DIORITE : 117712 Z: 52..86
GRANITE : 179526 Z: 38..93
PHYLLITE : 62071 Z: 42..87
MARBLE : 50621 Z: 45..82
SLATE : 54519 Z: 59..63
GABBRO : 139572 Z: 38..77
SLADE : 28212 Z: 18..24
>>> TOTAL = 970704
Ores:
MAGNETITE : 42071 Z: 92..99
TETRAHEDRITE : 15739 Z: 45..91
CASSITERITE : 9986 Z: 74..89
NATIVE_GOLD : 6267 Z: 38..92
NATIVE_SILVER : 6210 Z: 68..92
GARNIERITE : 4587 Z: 38..49
MALACHITE : 3846 Z: 45..51
RAW_ADAMANTINE : 1902 Z: 23..46
SPHALERITE : 1304 Z: 42..44
NATIVE_PLATINUM : 598 Z: 39..49
HORN_SILVER : 145 Z: 90..92
>>> TOTAL = 92655
Gems:
CITRINE : 1512 Z: 38..99
CRYSTAL_ROCK : 1271 Z: 38..85
AMETHYST : 1091 Z: 38..85
QUARTZ_ROSE : 987 Z: 39..98
PYRITE : 932 Z: 42..92
YELLOW ZIRCON : 911 Z: 42..89
RED PYROPE : 633 Z: 50..81
MILK QUARTZ : 631 Z: 38..91
CLEAR TOURMALINE : 592 Z: 50..82
SARDONYX : 574 Z: 92..99
TANZANITE : 565 Z: 38..73
BROWN ZIRCON : 514 Z: 38..92
MORION : 450 Z: 50..92
ALMANDINE : 442 Z: 68..87
BLUE GARNET : 436 Z: 45..61
SMOKY QUARTZ : 433 Z: 63..76
GREEN TOURMALINE : 347 Z: 44..78
RED ZIRCON : 347 Z: 52..91
PINEAPPLE OPAL : 318 Z: 93..99
BLACK ZIRCON : 308 Z: 39..91
VIOLET SPESSARTINE : 304 Z: 56..89
CLEAR GARNET : 288 Z: 38..87
CLEAR ZIRCON : 277 Z: 45..92
GREEN JADE : 271 Z: 93..99
PINK JADE : 267 Z: 92..98
CAT'S EYE : 242 Z: 74..92
PERIDOT : 234 Z: 74..76
BROWN JASPER : 228 Z: 93..99
YELLOW JASPER : 221 Z: 93..99
WAX OPAL : 217 Z: 59..62
BLACK PYROPE : 213 Z: 56..91
MILK OPAL : 202 Z: 74..76
PINK GARNET : 191 Z: 68..89
SPINEL_PURPLE : 188 Z: 58..87
SCHORL : 185 Z: 45..73
PIPE OPAL : 182 Z: 56..58
RUBICELLE : 179 Z: 59..91
EMERALD : 169 Z: 45..89
LAPIS LAZULI : 167 Z: 62..76
INDIGO TOURMALINE : 166 Z: 59..62
CHRYSOBERYL : 143 Z: 68..92
BLUE JADE : 137 Z: 92..98
SPINEL_RED : 136 Z: 81..87
MORGANITE : 116 Z: 46..78
GREEN ZIRCON : 114 Z: 46..92
KUNZITE : 107 Z: 90..92
PINK TOURMALINE : 103 Z: 46..61
GOLD OPAL : 102 Z: 93..99
OPAL_BANDFIRE : 94 Z: 45..51
FIRE OPAL : 90 Z: 74..78
HELIODOR : 83 Z: 86..89
TSAVORITE : 74 Z: 79..82
MOONSTONE : 73 Z: 42..82
GOSHENITE : 68 Z: 38..78
YELLOW SPESSARTINE : 62 Z: 68..80
MOSS OPAL : 58 Z: 45..51
OPAL_PINFIRE : 58 Z: 74..78
ALEXANDRITE : 57 Z: 74..78
RED GROSSULAR : 57 Z: 46..51
RHODOLITE : 52 Z: 88..91
PRASE OPAL : 50 Z: 58..61
PRASE : 44 Z: 86..89
AMBER OPAL : 40 Z: 68..73
YELLOW GROSSULAR : 32 Z: 45..50
RESIN OPAL : 30 Z: 40..92
OPAL_BLACK : 30 Z: 38..41
CHERRY OPAL : 18 Z: 42..44
RED TOURMALINE : 16 Z: 84..85
ONYX OPAL : 11 Z: 42..44
TOPAZOLITE : 2 Z: 51
>>> TOTAL = 19742
Other vein stone:
MICA : 44061 Z: 50..92
OLIVINE : 23762 Z: 38..49
MICROCLINE : 17869 Z: 82..91
COBALTITE : 14494 Z: 58..91
COAL_BITUMINOUS : 6180 Z: 93..99
LIGNITE : 4977 Z: 93..99
ORTHOCLASE : 3959 Z: 88..92
KIMBERLITE : 2783 Z: 38..49
HORNBLENDE : 868 Z: 50..92
RUTILE : 388 Z: 42..89
GRAPHITE : 314 Z: 51..91
PETRIFIED_WOOD : 260 Z: 93..99
ILMENITE : 217 Z: 62..67
SALTPETER : 188 Z: 92..98
PERICLASE : 119 Z: 45..82
PYROLUSITE : 111 Z: 68..92
CALCITE : 102 Z: 45..82
>>> TOTAL = 120652
Shrubs:
BERRIES_PRICKLE : 64 Z: 103
GRASS_TAIL_PIG : 57 Z: 88..90
BUSH_QUARRY : 48 Z: 88..90
MUSHROOM_HELMET_PLUMP : 46 Z: 88..90
MUSHROOM_CUP_DIMPLE : 40 Z: 89..90
POD_SWEET : 38 Z: 88..90
BERRIES_STRAW_WILD : 31 Z: 103
ROOT_HIDE : 29 Z: 103
GRASS_LONGLAND : 28 Z: 103
WEED_BLADE : 19 Z: 103
WEED_RAT : 4 Z: 103
BERRIES_FISHER : 1 Z: 103
REED_ROPE : 1 Z: 103
BERRY_SUN : 1 Z: 103
>>> TOTAL = 407
Wood in trees:
BLOOD_THORN : 226 Z: 64..68
TOWER_CAP : 127 Z: 88..90
FUNGIWOOD : 121 Z: 88..90
SAGUARO : 44 Z: 103
FEATHER : 37 Z: 103
PALM : 32 Z: 103
ACACIA : 27 Z: 103
WILLOW : 1 Z: 103
>>> TOTAL = 615
Has HFS tubes : 59 Z: 23..45
The world is the last one I posted in the World Gen cookbook thread, but the site is a different one (I decided I wanted fire clay, 'cos Phoebus makes Earthenware Brick Constructions brown, & Stoneware Brick White [or a VERY light grey]), & yes, it does look like I'm going to have to import
Flux if I can find all the Iron ore.
Edit: Oops, should probably note, I use Advanced World Gen settings, for the fine control over my worlds.