# Black Donald Graphite Specimen — BDG-01

**Status:** Candidate PCM thermal-conduction/nucleation material; not yet
characterized or approved for formulation use  
**Recorded:** 2026-08-13  
**Project role:** RevB PCM bench screening for possible later Rumi/RevC use

## Provenance

`BDG-01` is a softball-sized, graphite-rich rock recovered underwater near the
shore at approximately `45°13′26.4″N, 76°54′48.6″W`. Keep the exact coordinate
private in public-facing material because it also identifies the cottage area.

The Ontario Mineral Inventory point for the former Black Donald Mine/tailings
is `45°13′28.8″N, 76°54′49.5″W`, approximately 77 m from the reported recovery
location. The point lies beside a former access route to the mine and company
town, near an abrupt underwater drop-off. The specimen could be mine ore,
waste rock, tailings-area material, or material lost from historic haulage;
the specific path cannot be established from location alone.

Photographs are stored in:

- `Camera/IMG_19800112_122845.jpg`
- `Camera/IMG_19800112_122850.jpg`

## Historical and geological ground truth

The Black Donald deposit was discovered in 1889 and produced from 1896 to
1954. Government records describe flake, amorphous, and crystalline graphite.
Reported ore grade varied substantially: an early estimate gave approximately
65% graphite, later operating ore averaged approximately 25–30%, historic
analyses ranged broadly, and selected flake concentrate exceeded 98% carbon.

Recorded associated minerals include apatite, pyrite, pyrrhotite, tremolite,
tourmaline, quartz, mica, diopside, scapolite, and carbonate minerals. The
photographs are visually consistent with massive graphite-rich ore containing
lighter and bronze-toned inclusions, but a photograph cannot identify or
quantify those phases.

The mine suffered collapses and flooding, including the decisive collapse of
1950. Surface/open-pit recovery continued until closure in 1954. Construction
of the Mountain Chute project permanently submerged the mine and town in 1967.
The nearby gravel structure visible on current imagery is consistent with the
associated reservoir embankment/closure dam, not a generating station.

## Survey status

No publicly available systematic underwater archaeological or sonar survey of
the submerged mine/town was located during the 2026-08-13 review. Ontario's
Abandoned Mine Inventory records a 2008 tailings assessment for AMIS site
`02217`, but the underlying report was not found publicly. A future records
request could ask for that assessment plus associated maps, photographs,
bathymetry, inspection notes, sonar data, and mine plans.

## Candidate NanoArc use

The specimen may be useful as:

- a graphite-rich thermal-conduction scaffold or coarse fraction;
- a persistent heterogeneous nucleation surface in a controlled SAT screen;
- an inclusion in a separate beeswax thermal-response specimen; or
- a geological reference against commercial expanded graphite.

It must not be treated as pure graphite or added to a production PCM before
characterization. Unknown sulfides, silicates, carbonates, and hydrate/corrosion
interactions could compromise repeatability or containment.

## Minimum characterization before use

1. Photograph and weigh the intact parent specimen.
2. Record paper mark/streak, hardness, magnet response, and electrical
   resistance at several locations and orientations.
3. Remove only a small labelled sacrificial chip from a natural projection.
4. Use wet, dust-controlled sampling with eye and respiratory protection;
   possible silica/tremolite and sulfides make dry crushing inappropriate.
5. Inspect the fresh fracture under magnification and separate any magnetic
   fraction from a small processed sample.
6. Test first in a sealed beeswax comparison against pure beeswax and a
   commercial graphite control.
7. Only then consider a sealed SAT micro-screen, with a pure-SAT control and a
   separately identified formulation.

Any resulting formulation must receive its own ID, exact graphite-rich fraction
mass, preparation method, particle-size range, source record, and thermal-cycle
dataset. Geographic provenance is strong evidence of origin, not a quantitative
assay.

## Principal records

- Ontario Mineral Inventory: `MDI31F02NW00006`, Black Donald Mine.
- Ontario Abandoned Mine Inventory: `02217`, Black Donald Graphite Mine.
- Geological Survey of Canada Memoir 195, pages 22–25, DOI
  `10.4095/100827`.
- Canada Mines Branch Publication 511, *Graphite*, pages 35–38, DOI
  `10.4095/307722`.
- D. F. Hewitt, *Graphite in Ontario*, Industrial Mineral Report 20,
  pages 45–56.