(For the beginning player, see also The Non-Dwarf's Guide to Rock)
Stone is divided into a few key categories:
- Metal ore: stone that produces metal bars when smelted
- Rough gems: rough gems can be cut, then used to encrust objects and create windows.
- Other stone: Stone that is not an ore or a gem. Few of these have a use outside of items and structures. (Obsidian is one exception).
Economic stones are types of stone that can be reserved for a special purpose. For ores, this is smelting and for fluxes, this is steel production. Bituminous coal and lignite can be reserved for making coke.
Having created loose stone, many times you'll want to get rid of it or at least move it someplace else. See stone management for advice.
 Main layer types
There are four types of stone layers (plus soil, which is not stone). The type of layer is the primary indicator of what kind of ores you are likely to find on the map, as well as a sign of volcanic activity.
 Stones forming entire layers
These types of stone occur as entire layers, containing some veins and pockets of other minerals (see below). If one of the following types of stone is present on your map, it will be listed in one of the biomes on the embark screen.
|Sedimentary||Igneous intrusive||Igneous extrusive||Metamorphic|
- (* These stones are practically identical within the game, distinguished only by their names and their un-mined presentation on the map. See basalt for the sole minor difference.)
 Other Stone
Stones found on this table will occur as pockets and veins inside their respective stone layers (see above). When your miners newly encounter one of them, the game will pause and you will receive an announcement; even for the ones that have no use other than to build constructions of unusual colors. Note that the veins or clusters can spread into other layers, and may cause some layers to contain stones they usually wouldn't. A few of these stones, such as Olivine, have other, more interesting minerals appear inside them.
Non-layer stone formations occur in one of three shapes: large clusters, veins, and small clusters. (See Veins & Clusters for full info.)
- (L) - occurs in large clusters
- (V) - occurs in veins
- (S) - occurs in small clusters
- (1) - occurs in individual tiles
 DF Geology and real-world Geology
The geology and stones of Dwarf Fortress are based on real-world geology and mineralogy. To understand the terms used here, you may want to crack open a geology textbook (a high school one should suffice). If you don't happen to have one close by, the Wikipedia articles for geology, mineralogy, or the terms in question might help.