I don't hink I have ever seen a tetrahidrite or an obsidian asteroid produce diamonds. Those come primarily from ice, although rocky asteroids will yield one on rare occasions, and they are reasonably often found in the black pyroclastic "spindles" in rocky asteroid fields.
Rocky asteroids yield lare amounts of metal ore, usually 2-3 per minable rock, and occasionally 1 obtainium. On rare occasions 2 obtainium will in the matrix. (Once or twice I've seen three.) In very rare instances, a rock will yield a gold ingot, or even more rarely, a meteroic diamond.
The rocky fields also usually have 0 to 3 black pyroclastic spindles, which most often yield 3 to 5 obtainium, but occasionally have 1-3 gold ingots. Moderately rare drops from spindles are 1-2 metoric diamonds, or 1-2 alien artifacts. This is the primary source for alien arifacts.
Ice fields are spread out far more than most asteroid belts, and they have a far sparser density of mineable "lumps". Instead of ~20 mineable items in a typical asteroid field, a typical ice field might have 4-5 worthwile exploitable "bergs". I believe 9 in one really gigantic ice field spread out over about 70sm id the most I have ever seen. However, the value of most of the minable deposits is far higher than the bulk of the output from rocky asteroid fields. About one berg out of five will have just a bit of near worthless metallic ore. The other deposits will be about equally distributed densities meteroic diamonds, tachyon salt, and pure water. Ice bergs are the only environmental sources for tachyon salt and pure water, and the ice is also the primary source for meteroic diamonds.
Tetrahidrites are clumps of near pure metal crystals, with the typical crystal "prismatic" or "spear" shapes sticking out of the body. (These things really exist in nature under rare conditions, but the game presumes really huge ones, and occasionally really really very huge ones, forming in space.)
Tetrahidrite asteroids yield small amounts (singles) of metallic ore, very occasionally obtainium (maybe 1 or 2 in a belt), rarely a gold ingot, and really, really rarely a Face of Gozu.
(Except in the special, no-more-than-once-in-any-system, "field of gigantic tetrahidrites", each of which shows a Face of Gozu and several gold when scanned, but only yields a Face + 1 gold.)
Obsidian/flint/glassy asteroids look like lumps of black or brown volcanic glass. Well, actually that's what they are. Obsidian asteroids yield low yields of metallic ore and obtainium, just like the tetrahidrite fields. The super extra rare drop that is possible in an obsidian asteriod is an antimatter speck, sometimes in combination with a gold ingot. I believe I have found this twice, once with gold, once without, in the several hundred glassy asteroids I have mined. I don't think I have ever found a separate deposit of gold in an obsidian field, but it wouldn't surprise me. This is apparently the only mineable source of antimatter specks.
(There is also a special no-more-than-one-field-per-system variation for glassy asteroids. It has a small number (2-4?) of gigantic obsidian asteroids, each of which contains an antimatter speck. At least some of them have a gold ingot.)
A small number of rocky asteroid fields have an admixture of crystaline asteroids of various colors, mostly dirty yellow, pinkish, or greenish. When these are designated as mineable they contain about the same proportions of metallic ore/obtainium as most of the rocky asteroids. Crystaline asteroids only have one deposit in them, AFAIK. They also have no detectable fault points.
Once in a blue moon made from cheese (and note that all the moons in Rebel Galaxy are gray), a rocky asteroid field will include a large striking-looking crystalline asteroid with blue crystals growing from a lavender-ish rock base. At least sometimes, such an asteroid contains a Progenitor Shard. This appears to be the only mineable source of Progenitor Shards in game.
Whew. What I started to be a short response to Zid seems to have turned into my essay and resource page on all mineable items in Rebel Galaxy. I like mining in the game and I have mined a lot (a LOT - est. 10,000+) of asteroids and bergs. Please let me know of any omissions or errors, or new tidbits, and I will add them.
Special Note on Scanning for Miners.
IF you have a laser turrret (considered by the game to be the minimum of mining gear...although you really have to have a tractor beam as well, to pick up the extracted valuable bits), you can scan the interior make-up of mineable asteroids. This allows you to:
a) pick out the best deposits to extract to fill your limited hold space; or
b) see which asteroids have multiple deposits, and therefore require a fault tracker to get full value from heat extraction (i.e. blowing up the asteroid with a laser); or
c) identify asteroids that only have single deposits of any given mineral, thereby saving a little time since you don't have to carefully mine them with a fault tracker.
d) identify the many asteroids that contain only Metallic Ore, and aren't worth bothering with. (It would take ~10 initial SHIPLOADS of Metallic Ore to even pay for your basic Tractor Beam and Mining Laser.)
To scan an asteroid interior:
a) Pulse the asteroid field to identify the mineable resources / rocks / bergs.
a) Switch your weapon control to Laser Turrets.
b) Place the aiming reticle / cursor on a mineable asteroid.
d) Scan by holding down the LMB.
After a moment, the detected interior depoisits will be listed below the other scan data at the upper right of the screen.
Special Note on Asteroids with Multiple Mineral Deposits, and Mining Technique.
If an asteroid has multiple types of mineral deposits, and you just blast it apart without a Fault Tracker to guide your shot, it will still yield 1 tonne of EACH TYPE of mineral that is present. This means that if you find an asteroid that has 1x Metallic Ore, and 1x Obtainium, there is no need to worry about finding the right spot to shoot to extract both items; just blast it.
If the scan shows multiple deposits of the SAME mineral, to get the full yield of everything you will have to Pulse with a Fault Tracker installed, and shoot at one of the target spots identified by the Fault Tracker (red tic mark circles). Believe me, if you scan a lump of lava with 2x Alien Artifacts imbedded, you're really going to want to do everything you can to carefully extract BOTH of them. Oh, and your ship will need to be within ~1.4 sm of the rock for you to SEE the fault target circles.
Your laser targeting system can still pick up the fault targets out to the limit of your laser's range; it will soft lock the laser aim point on the fault. However, if you can't see the red aiming circle, the fault might be on the opposite side of the rock. You can chance the shot, but if you shoot through the body of the rock to hit the locked fault, you will get minimum yield just as if you had shot center of mass. With practice, you can get a feel for the way the lock point moves with the rotation of the asteroid and get better at identifying when the fault is in direct line of fire, but it is still best to SEE the Fault Tracker target circle and be sure.
Post edited June 30, 2017 by dreamrider