As the name suggests, these are rocks made from flakes and may have different compositions. They may be of dolostones/dolomites (flake-breccias) origin (Fairchild, 1980) or
they may be of mudstone (mud-flake breccias) origin (Fairchild, 1980, Pickering, 2005).
I have so far, mostly come up with them being formed in marine settings; be it shallow or deep, but that maybe because I am biased towards reading more about marine carbonates.
In the shallow marine, these flakes are usually related to dessication cracks where after forming the cracks these flakes can be found within those cracks that are more susceptible to erosion as they get transported to those 'depressions'. (See figure below)
Another creation of the flakes may be due to sliding or slumping of the material as found in the more deeper marine settings. And whence formed into a rock, it's called a flakestone.
Flakestone portion as part of a flake pocket of dolostone flakes (Adapted from Fairchild, 1980)
My initial idea was that these flakestones were similar to conglomerates. In a manner, they are a type of breccia more than conglomerate since they may form due to slides and slumps and are more pointy at both the edges.
I hope one day that I will come across a flakestone and thus be no longer confused!
References
Fairchild, I. J., 1980. Sedimentation and origin of a Late Precambrian 'Dolomite' from Scotland. Journal of Sedimentary Petrology, v. 50, n. 2, p. 0423-0446.
