The phrase "because they were composed" is correct and usable in written English.
It can be used to explain a reason related to the composition of something, such as a piece of music, a text, or a group of people.
Example: "The audience was captivated by the performance because they were composed of talented musicians."
Alternatives: "due to their composition" or "as they were created."
Both cores were likely too weak to withstand the pressure because they were composed of a concrete mixture that used nitrogen gas to accelerate curing.
They tasted of nothing much, and that was just as well, because they were composed of muscle, gristle, head-meat and tail, padded out with rusk, injected with 11 chemicals and stuffed in a plastic tube.
These agents, so called because they are composed chemically of three carbon rings, inhibit the active reuptake, to varying degrees, of norepinephrine, serotonin, and dopamine in the brain.
The last on this list is one of the most intriguing of Francis's bodily peregrinations – for our lungs turn out to be the least dense organs in our bodies, and that is because they are composed almost entirely of air.
The polysaccharides, such as chitosan, are polyhydroxy compounds because they are composed of numerous monosaccharide residues.
Indeed, although their ecotoxicological profile is still poorly known, DES are classified as "green" solvents because they are composed of molecules which are considered to be eco-friendly.
The traditional geometric primitives recognition algorithms can recognize primitives, but the real elements can be large and complex because they are composed of several geometric primitives.
The term multi-step is assigned to these complex attacks because they are composed of different steps, either legal or not, with no evident link between them.
In these hybrid systems, phase separation occurs naturally because they are composed of two materials with totally different chemical characteristics [5 7].
