The phrase "is mainly formed" is correct and usable in written English.
It can be used when describing the primary composition or structure of something.
Example: "The committee is mainly formed of volunteers who are passionate about community service."
Alternatives: "is primarily composed" or "is chiefly made up".
The BBB is mainly formed by brain capillary endothelial cells, pericytes, astrocytes, and neuronal cells17.
Sometimes it occurs to me there's an inborn pattern in people's minds which is mainly formed by religious concepts".
K-struvite is mainly formed with probably more phosphate than the theoretical value.
Pure NaV6O15 bronze is mainly formed from gels containing a Na/V ratio of 0.18.
For the other ketones, the 1/1 species is mainly formed.
Third it reveals that lithium carbonate is mainly formed by irreversible chemical conversion of lithium oxygen species upon air exposure.
At higher boron content, TiB2 is mainly formed and the B2 structure disappears with the concurrent formation of a highly disordered Ru-rich phase.
The μ-Ag3Al phase is mainly formed in the region between the columnar Al layer on the surface and the Ag substrate.
When methane is replaced by either MEK or EA, the NO mole fraction in the burned gases and the CH peak value are found to jointly decrease, indicating that NO is mainly formed according to the prompt-NO mechanism.
Glancing angle X-ray diffraction (GAXRD) measurements showed that rutile is mainly formed in the inner part of the film, meanwhile anatase phase remains in nanotube crystals (outer part), even at 700 °C.
The conformational model thus obtained indicates that the PDPP chain is mainly formed by sequences of about four skeletal bonds in the trans conformation separated by one bond in cis, with negligible incidence of cis cis orientations.
