  Rocky planet compositions regulate planetary evolution by affecting core
sizes, mantle properties, and melting behaviours. Yet, quantitative treatments
of this aspect of exoplanet studies remain generally under-explored. We attempt
to constrain the range of potential bulk terrestrial exoplanet compositions in
the solar neighbourhood (<200 pc). We circumscribe probable rocky exoplanet
compositions based on a population analysis of stellar chemical abundances from
the Hypatia and GALAH catalogues. We apply a devolatilization model to simulate
compositions of hypothetical, terrestrial-type exoplanets in the habitable
zones around Sun-like stars, considering elements O, S, Na, Si, Mg, Fe, Ni, Ca,
and Al. We further apply core-mantle differentiation by assuming constant
oxygen fugacity, and model the consequent mantle mineralogy with a Gibbs energy
minimisation algorithm. We report statistics on several compositional
parameters and propose a reference set of (21) representative planet
compositions for using as end-member compositions in imminent modelling and
experimental studies. We find a strong correlation between stellar Fe/Mg and
metallic core sizes, which can vary from 18 to 35 wt%. Furthermore, stellar
Mg/Si gives a first-order indication of mantle mineralogy, with high-Mg/Si
stars leading to weaker, ferropericlase-rich mantles, and low-Mg/Si stars
leading to mechanically stronger mantles. The element Na, which modulates
crustal buoyancy and mantle clinopyroxene fraction, is affected by
devolatilization the most. While we find that planetary mantles mostly consist
of Fe/Mg-silicates, core sizes and relative abundances of common minerals can
nevertheless vary significantly among exoplanets. These differences likely lead
to different evolutionary pathways among rocky exoplanets in the solar
neighbourhood.
