Luzonite is a somewhat rare copper arsenic sulfide mineral that is dimorphous with Enargite. This means the two minerals that have the same chemical formula (Cu3AsS4) but different crystal structures. Luzonite is Tetragonal and Enargite is Orthorhombic. Luzonite is opaque with metallic luster, Moh’s hardness of 3.5 and very dark pinkish brown color.Locations for Luzonite: from the type locality [TL] at the Lepanto mine, Mankayan, Luzon, Philippines, as an ore mineral. In the Chinkuashi mine, Keelung, Taiwan. In Japan, at the Teine, Morino, and Date mines, Hokkaido; the Kasuga and Akeshi mines, Kagoshima Prefecture; and other localities. From the Sierra Famatina, La Rioja Province, Argentina. In the Julcani district, at Cerro de Pasco, and at Huaron, Peru. In the USA, in Nevada, at Goldfield, Esmeralda County, from the Golden Chariot mine, Jamestown district, Nye County, and in the Burrus vein, Pyramid district, Washoe County; from Butte, Silver Bow County, Montana; and at Summitville, Rio Grande County, Colorado. At the Chelopech deposit, Sofia, Bulgaria. From Calabona, Sardinia, Italy. At the Kadzaharan deposit, Armenia. From Pîrîul lui Avram, Romania. In the Lahóca Hill mine, Recsk, Mátra Mountains, Hungary. Numerous additional localities are now known.
| Chemical Formula: | Cu3AsS4 |
| Copper Arsenic Sulfide | |
| Molecular Weight: | 393.82 gm |
| Composition: | Copper | 48.41 % | Cu | ||
| Arsenic | 19.02 % | As | |||
| Sulfur | 32.57 % | S | |||
| 100.00 % |
| Crystallography: | Tetragonal – Scalenohedral |
| Crystal Habit: | Crystals rare, to 2 mm; commonly coarse-grained, fine-grained, massive, intimately intergrown with Enargite. |
| Twinning: | Common on {112}, also polysynthetic in polished section. |
| Cleavage: | Good on {101}, distinct on {100} |
| Fracture: | Irregular/Uneven, Conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 3.5 |
| Density: | 4.38 – 4.60 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Health Warning: | Contains Arsenic – always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest. |
| Color: | Deep pinkish brown, similar to Bornite, although darker; in polished section, pale brownish pink |
| Transparency: | Opaque |
| Luster: | Metallic, dull |
| Refractive Index: | R1–R2: (400) 27.2–28.7, (420) 25.6–27.6, (440) 24.1–25.6, (460) 23.6–24.7, (480) 23.4–24.5, (500) 23.7–25.2, (520) 24.1–26.4, (540) 24.3–27.1, (560) 24.9–27.7, (580) 25.6–28.5, (600) 26.5–29.1, (620) 27.3–29.6, (640) 28.1–29.9, (660) 28.6–30.1, (680) 28.7–30.0, (700) 28.7–30.0 |
| Birefringence: | 0.000 (opaque) |
| Dispersion: | n/a |
| Pleochroism: | Weak |
| Anisotropism: | Strong, in greenish yellow and purplish |
