Hiya guys i need a seed that provides food and surface ores or a cave with ores, that would be enough Thnx

Hi folks, I'm still searching for Cassiterite, and finally (!) happened across two precious small surface ores. They were spaced about 20 blocks apart, in a Dolomite area (?!), atop a small, flat hill. (I literally gasped when I read the tooltip. I've been looking for ages.) I immediately got to work with the propick. Nothing of interest (except tons of Lignite and a smattering of other stuff)at the surface anywhere within about 50 blocks of each of the samples I found. So I dug into the cliff about 15 blocks beneath the flat hilltop. After a little bit of haphazard prospecting, with no results other than the copious amounts of coal, I dug a long prospecting gallery straight through the hill. Still no Cassiterite on the propick. I opened up three cross galleries, spaced 24 blocks apart, each themselves 48 blocks long (24 in either direction). Now my system precisely and completely covered a 72×72×24 area centered at y=151 beneath the midpoint of the two surface samples, which were spaced apart about ⅓ of that.And yet still no Cassiterite, even after propicking every single floor block in each of my three cross galleries and long main gallery. So I dug down another 24 blocks, just into the middle layer of stone (which is Andesite), and did the same. Still nothing. And nothing again a further 24 blocks down, over 50% into the middle layer. I've now completely covered a 72×72×72 cube, and not a single hint of Cassiterite on the propick. There's plenty of other stuff down there: Lignite, Saltpeter, Hematite, Native Copper, Jet, Bismuthinite, and even Bituminous Coal. But no Cassiterite. I suppose there is the unlikely possibility that every single space I've propicked just happened to randomly choose to report either nothing or something other than an extant Cassiterite deposit nearby. But the odds against that have to be enormous, with every single centrally-located block (within 12 of a main gallery) getting included in over 48 propick searches, and all outlying blocks (along side galleriesfurther than 12 from a central gallery) getting included in 24. Does anyone know the precise game mechanics of surface ores? Are they supposed to always indicate an underground vein, or are there sometimes false positives? The wiki says they're supposed to indicate a vein somewhere between the surface and, at furthest, the upper part of the middle layer. I've more than covered that. But what about distance on the x–z plane? If you consider each surface sample to be off-center by about ⅓, technically the coverage beneath each ore is lopsided: 24 blocks in one direction, 48 in the other, and 36 on either side. Should I expand my area? dig deeper? Or should I just consider it a false positive and move on? Gracias. Edit: I understand and respect the devs' embargo on publishing magic numbers and gameplay mechanics, so I'm not necessarily looking for an algorithm. But I think it's fair to ask whether surface oresalways indicate underground veins or whether there are false positives. And if the former, I think it's also fair to get a relative sense of how close to expect underground veins to be on the x–z plane (e.g., "directly beneath", "pretty close by", "within a few chunks", "anywhere in the area of that stone type"), similar to the relative description of depth listed on the wiki.