Phlogopite with Chalcopyrite
Phlogopite (Magnesium-rich Mica) and Chalcopyrite (Copper Iron Sulfide) · Mineral Specimen / Collector Mineral
Crystal System
Monoclinic (Phlogopite - micaceous sheets); Tetragonal (Chalcopyrite - massive or tetrahedral habit)
Mineral Group
Silicates (Phyllosilicate Subgroup) and Sulfides
Chemical Formula
KMg3(AlSi3O10)(OH)2 [Phlogopite] + CuFeS2 [Chalcopyrite]
Formation Process
Metamorphic or Igneous; typically forms in contact metamorphic zones (skarns), dolomitic marbles, or ultramafic rocks through hydrothermal fluid interaction.
About This Crystal
The specimen features a dark, platy matrix of Phlogopite mica with a vitreous to pearly luster. Embedded within and on the surface are brassy, metallic yellow grains of Chalcopyrite. The Phlogopite appears dark brown to nearly black, while the Chalcopyrite provides a golden-metallic contrast. The texture is craggy and irregular, showing flaky exfoliation characteristic of mica minerals.
Physical Characteristics
Color: Bronze-brown to black (Phlogopite), Brass-yellow (Chalcopyrite); Streak: Colorless/White (Phlogopite), Greenish-black (Chalcopyrite); Specific Gravity: 2.7–2.8 (Phlogopite), 4.1–4.3 (Chalcopyrite); Cleavage: Perfect basal (mica); Fracture: Uneven/Splintery; Fluorescence: Usually inert.
Optical Properties
Phlogopite is biaxial negative with high birefringence but often obscured by opacity in thick specimens. Chalcopyrite is opaque and metallic with no light transmission.
Hardness & Durability
Origin Region
Commonly found in Canada (Bancroft, Ontario), Madagascar, Russia (Kola Peninsula), and various skarn/marble deposits globally.
Hardness & Durability
Phlogopite: 2.5–3.0 (Very soft, scratched by a fingernail or copper coin); Chalcopyrite: 3.5–4.0. Both are brittle and sensitive to physical impact.
Care & Maintenance
Avoid ultrasonic and steam cleaning. Use a soft brush and cool water. Keep away from high humidity as Chalcopyrite can oxidize over time. Store separately to prevent the soft mica from being scratched by harder stones.
Rarity & Value
Relatively common mineral combination for industrial and geologic specimens. Value is primarily aesthetic for collectors, ranging from $10 to $50 for hand-sized pieces depending on the quality of the metallic inclusions.
Special Characteristics
The mica displays a high degree of flexibility in thin sheets. Chalcopyrite may develop a multi-colored iridescent tarnish (bornite-like) if exposed to certain environmental acids.
Lore & History
Phlogopite is historically used as an electrical insulator due to its heat resistance. In metaphysical lore, micas are believed to aid in mental clarity and retrospection, while Chalcopyrite is often associated with removing energetic blockages and enhancing perception.