TL;DR: Graphite/Carbon phases is a main entry in the 外星矿物知识引擎 database.
Carbon phases in meteorites and lunar samples provide a critical reagent for ISRU processes. Carbon is needed for carbothermal reduction of metal oxides and as electrode material in molten electrolysis. Carbonaceous chondrites are the richest source, containing up to 5% carbon.
Crystal System
Hexagonal (graphite)
Occurrence
Found in ureilite meteorites; present in some lunar samples; carbonaceous chondrites contain up to 5% carbon
Significance
Source of carbon for carbothermal reduction; electrode material for electrolysis; lubricant for space mechanisms
Source
Meteorite analysis, lunar sample studies