GregTech disables all Vanilla ores (except Emerald Ore, Twilight Forest Hollow Hills, and Nether Quartz spawned around hives in the Nether), and replaces them with its own ore generation system.
Just walk on the surface and “This is a ore chunk” will appear in the upper left corner.
Each prospector has a different durability / range of chunks , depending on what materials it is made of.
These ores generate in any dimension. They are intended as a way to get small amounts of raw materials useful for tools. They are not intended to be used as a primary source of resources for progression or machinery. When broken, they drop either a Crushed Ore, an Impure Pile of Ore Dust, or, if applicable, a Gem, of the respective ore. Additionally, they may drop a Dust or a Dirty Dust of the stone type they were found in. Small Ores cannot be picked up with a Silktouch Pickaxe, however a Fortune Pickaxe will slightly increase their yields. Importantly, Small Ores can be mined at 1 mining level lower than the ore itself, allowing a player with a stone-level pickaxe to mine iron-level ores.
Mix Veins come in four parts, Primary, Secondary, Inbetween, and Around. Each of these parts can be a different ore. Each mix will always be 9 blocks tall, or in other words have 9 levels (unless unnaturally cut off by dirt/air/non-stone type blocks), in all dimensions, except Galacticraft ones. The Primary part is contained in the top-most 4 layers, Secondary the bottom-most 4 layers, Inbetween the 4th to 7th layers, and Around can be found randomly anywhere in the 9 layers in much smaller amounts.
As you progress, it is important to use available tools to make sure you are mining as efficiently as possible. Once you get a jetpack, you can quickly move from center to center, as well as dig down without needing any sort of staircase to move back up the shaft. The Coal jetpack is the first decent pack, with the Copter pack being excellent for this. Just be aware of their limitations (ie, copter pack won’t work in water).
The other important thing is to replace your pickaxe/hammer head as you tier up. You can also mix and match the materials for some good effects, such as perditio large plates with a vanadiumsteel head. Some good fast mining materials to keep an eye out for:
Periditio (Thaumcraft shards) - Even if you don’t plan to use Thaumcraft, Perditio shards can be used to make hammer and pick heads with very high mining speeds. Their drawback is the low durability, so be prepared to repair often with the shards, which can get expensive.
Vanadiumsteel - Almost as fast as Peridtio, but with very high durability. Takes a really long time in the MV extruder to make a head - ~30 minutes!
Shadowmetal - Available from the Tainted Magic mod under the Malefica tab. High durability, really high mining speed. Costs some Warp to research, and requires alchemy to make. Also requires vacuum freezer to cool the hot ingots for use.
Traveller’s Glove (Tinker’s Construct) - This useful item will make your mining even faster. Load it up with Redstone and it will accelerate your mining speed.
Traveller’s Belt (Tinker’s Construct) - This is an really useful item since it will give you an additional Hotbar. Use it to store your mining equipment or GT tools.
Jetpack (especially Copter pack) - The copterpack can be left on in normal mode, where it slowly falls as material underneath you is removed. It does slow mining speed slightly, but much less than hovering.