Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons
Massive millerite is sometimes cut into a cabochon by a collector or sliced into slabs for decorative purposes. The yellow color is very rich and attractive, and the cut gems are indeed curiosities. The mineral is too soft for wear. Massive millerite is of no great interest to mineral collectors and therefore might be difficult to obtain in the marketplace, although it is abundant at certain localities.
Millerite Value
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Millerite Information
| Data | Value |
| Name | Millerite |
| Crystallography | Hexagonal. Crystals capillary or acicular; tufted; fibrous; also massive and cleavable. |
| Colors | Brassy and bronze yellow; tarnishes greenish gray. |
| Luster | Metallic; opaque. |
| Hardness | 3-3.5. |
| Density | 5.3-5.6. |
| Cleavage | Perfect 2 directions. Fracture uneven. Brittle; |
| Stone Sizes | Cabochons of any size could be cut from massive material. |
| Formula | NiS. |
Streak: Greenish black.
Occurrence: A low-temperature mineral in limestones and dolomites, serpentines, and ore deposits in carbonate rocks.
Illinois; Wisconsin; Iowa.
Wales; Czechoslovakia; Germany.
Antwerp, New York: fine sprays of acicular crystals.
Gap Mine, Lancaster County, Pennsylvania; acicular tufts.
Missouri: in geodes.
Hall’s Gap, Kentucky: tufts of fibers in geodes.
Timagami, Ontario, Canada: large cleavable masses.
Comments: Massive millerite is sometimes cut into a cabochon by a collector or sliced into slabs for decorative purposes. The yellow color is very rich and attractive, and the cut gems are indeed curiosities. The mineral is too soft for wear. Massive millerite is of no great interest to mineral collectors and therefore might be difficult to obtain in the marketplace, although it is abundant at certain localities.
Name: After mineralogist W. H. Miller, who first studied the crystals.
