I am not a scientist and wanted to understand the geology. So I did a quick internet search. A very brief definition:

Limestone = marine sediment primarily calcite = calcium carbonate (CaCO3)

Sandstone = sedimentary rock = sand grains cemented together by calcite or silica

Paragneiss = metamorphosed sedimentary rock

Marble = metamorphosed, recrystallized calcite

Wallastonite = metamorphosed, formed from reaction between calcite and dissolved silica = Ca CO3 + SiO2 = Ca SiO3 + CO2

Graphite = Carbon that may have come from CO2 produced in chemical reactions

-occurs in metamorphic rocks as a result of the reduction of sedimentary carbon compounds during metamorphism

-Minerals associated with graphite include quartz, calcite, micas and tourmaline.

At CCB the graphite occurs at the contact between marble and paragneiss

SO HOW WAS THR GRAPHITE FORMED?

The veins formed by one of the following:

1. An intrusion of hydrothermal materials from the mantle

2. More likely the graphite was formed by the metamorphism of the calcite?

I am not a chemist or metallurgist so please weigh in on this.