Is amorphous graphite the same as earthy graphite?

Amorphous graphite—also known as earthy graphite, microcrystalline graphite, or black lead powder—does not actually lack graphite crystals as its name might suggest; rather, its crystals are extremely small, forming a microcrystalline structure. X-ray analysis reveals that amorphous earthy graphite contains 15% to 45% crystalline graphite, which is why it is also referred to as microcrystalline graphite.

Based on its mode of occurrence, amorphous earthy graphite can be classified into two types: disseminated earthy graphite ore and massive earthy graphite ore.

Disseminated earthy graphite ore primarily occurs within the fracture zones or along the cleavage planes of flake graphite deposits and exhibits a mylonitic structure. Its composition is complex and inconsistent, consisting mainly of plagioclase, quartz, graphite, tremolite, and chlorite. The graphite flakes are crushed into tiny fragments—sometimes appearing as pitch-black specks—making their crystalline form difficult to distinguish with the naked eye. The ore grade is low, typically ranging from 2% to 3%, and it lacks industrial value.

Massive earthy graphite ore is largely formed through the contact metamorphism of coal fields subjected to thermal alteration. The ore appears as dense, black masses and exhibits characteristics ranging from graphite to anthracite. Graphite content varies, generally falling between 60% and 80% (with a minimum of 15% and a maximum exceeding 90%); associated minerals include sericite, quartz, pyrite, calcite, limonite, and clay. These are the primary characteristics of earthy graphite.