Looking like polished black-chrome geometric stealth fighters bolted onto milky Quartz needles and snowy Barite blades, Peru's Huaron and Casapalca mines yield Earth's sharpest metallic Tetrahedrite crystals! Forming an unbroken chemical bridge between Antimony-rich Tetrahedrite (Cu12Sb4S13) and Arsenic-rich Tennantite (Cu12As4S13)—plus stuffing massive valuable Silver into Freibergite!—German miners nicknamed the whole crew 'Fahlore' (grey-pale ore)! Tune Sb/As chemistry, wrap mirror triangles in golden epitaxial Chalcopyrite jackets, and use subtle cherry-red vs black streaks to separate Sb from As without toxic tests!
Huaron Pasco Peru Mirror Tetrahedrite • Stealth-Bomber Sharp Triangles!
Formula: Cu6[Cu4(Fe,Zn)2]Sb4S13
Mechanism: Modified Isometric Tetrahedra Form Beveled Mirror Triangular Pyramids
Wait — Did You Know?Wait—how did Tetrahedrite get one of mineralogy's simplest names? Back in 1845 Wilhelm Haidinger literally looked at its razor-clean four-triangle pyramidal geometry—and named it 'Tetrahedrite' directly after the tetrahedron!
Select Specimen or Control Sample (8 Profiles)
Click any Tetrahedrite-Tennantite crystal, Chalcopyrite overgrowth, or metallic sulfide lookalike to compare streak & facets:
Antimony vs Arsenic Ratio, Silver Freibergite Load & Chalcopyrite Rim Coating
Slide Sb -> As to watch steel-black Tetrahedrite subtly sharpen into tin-bright Tennantite while trace cherry-red powder shows on heavy grind!
Hardness / Specific GravityMirror Chrome-Black Zero-Cleavage!
Morphology & CoatingOriginal Name From Shape Alone!
No Cleavage Signature: Unlike Galena cubes or Sphalerite diamonds, Tetrahedrite breaks cleanly with shiny glass-like conchoidal metal chips!
Why does this happen atom-by-atom? Read the 3-step physics strip below, then keep scrolling for Chapter 2 (Microscopic Atomic Zoom) and Chapter 3 (Interactive Real vs. Fake Split Loupe).
How The Crystal Physics Works (3-Step Flowchart)
Visual Mechanism Breakdown
1. Polymetallic Andean Veins Concentrate Cu, Sb, As & Silver
Pure zero-cleavage metal mirrors + black-cherry streak + zero magnet pull nail Fahlore cleanly against Galena cubes, Sphalerite cleavages, and Magnetite.
Chapter 2 of 3 • Microscopic Atomic Lattice Zoom
Inside The Lattice: Huaron Pasco Peru Mirror Tetrahedrite
Cubic I-43m: M12(Sb,As)4S13 — Unbroken Sb <-> As Swap + Ag+ Substitution (Freibergite Up To ~30 wt% Ag!)
Silver Concentration & Specific Gravity Across Fahlore Ore
Comparative Mineral Property Scale
Silver-Rich Freibergite (30% Ag Fahlore)Bright Pewter Mirror | SG 5.20 | Historic Ag Ore
Huaron Sb-Tetrahedrite (Peru Classic)Razor Mirror {111} Triangles | Zero Cleavage
Chalcopyrite-Jacketed TetrahedriteEpitaxial Brass-Gold Borders Over Chrome Core
Tsumeb As-Tennantite (Arsenic Member)Modified Dodecahedra | Dark Cherry-Brown Streak
❌ MYTH: All black metallic triangular pyramids from Peru are Tetrahedrite.
✅ FACT: Careful! Iron-rich Black Sphalerite grows exact mirror-image black tetrahedra inside the exact same mines—check carefully for Sphalerite's flat cleavage steps and light tan-yellow porcelain streak!
❌ MYTH: Bright brass-gold rims around black Tetrahedrite faces are fake painted gold leaf.
✅ FACT: 100% genuine epitaxial mineral overgrowth! Matching sulfur lattice spacing allows natural brassy Chalcopyrite (CuFeS2) to grow selectively along crystal bevels like natural gilded picture frames!
❌ MYTH: Tetrahedrite and Tennantite are completely unrelated ore minerals.
✅ FACT: They form a smooth continuous solid solution sharing identical Cu12X4S13 structure—literally trading Antimony (Sb) for Arsenic (As) cleanly across the middle!
Chapter 3 of 3 • Interactive Real vs. Fake Split Loupe
Authentic Specimen vs. Fake / Impostor Drag-Loupe
Drag the divider left/right — toggle Probe Mode for forensic lighting, cleavage & bubble inspection.
60-Second Pocket Field Test Checklist
Count symmetry cleanly: sharp 3-sided equilateral pyramid faces (tetrahedra or beveled edge stars) rather than cubes (Galena) or 8-sided Magnetite octahedra.
Inspect chipped spots at 10x: Fahlore fractures glassy conchoidally with ZERO flat cleavage mirrors—unlike Galena (90° steps) or Sphalerite (6 slanted resinous cleavage planes!).
Hold an N52 magnet near crystals to rule out black Magnetite immediately.
Always wash hands promptly with cold water and soap after handling Antimony- or Arsenic-rich metallic sulfide crystals.
Collector Caution & Fake Alert: SULFUR & TOXIC ARSENIC/ANTIMONY WASH NOTE: While clean crystal display pieces stay stable indoors, Tennantite packs Arsenic and Tetrahedrite packs Antimony (~30%!)—wash hands strictly after handling raw metallic specimens, keep out of humid acidic display shelves, and NEVER roast or scratch powder bare-handed!
High above 4,500 meters across Peru's rugged central Andes, silver-lead-zinc vein mines like Huaron and Quiruvilca exposed museum pockets bursting with mirror-sharp charcoal Tetrahedrite triangles standing proudly beside white Quartz, orange Rhodochrosite, and brass Pyrite!
🥈 Why German Miners Called It 'Fahlore' (Fahlerz)
Long before spectroscopes existed, medieval Harz & Freiberg silver miners split grey metallic ores carefully by eye into 'Fahlore' (greyish pale ore), noting its uncanny gift for secretly harboring huge Silver bullion fortunes once smelted!
👑 Epitaxial Gilding: How Chalcopyrite Frames Tetrahedrite
Because Chalcopyrite and Tetrahedrite both construct cubic-close-packed sulfur arrays, late iron-bearing solutions nucleated ultra-thin golden CuFeS2 fillets cleanly along reactive beveled edges—making stunning natural two-tone jewelry-grade cabinet specimens.
🧪 Safe Acid Rules For Sulfide Matrix Cleaning
Wait before pouring muriatic acid over dusty Barite or Calcite sitting on Tetrahedrite! Strong warm acid attacks sulfosalts slowly to stink of H2S gas and dull mirror chrome faces permanently milky—prefer gentle dry air puffs or brief cold mild cleaning strictly by pros.
Diagnostic Specimen Comparison Matrix
Quick Laboratory & Collector Reference
Mineral / Control
Formula & System
Key Physical Metric
Diagnostic Tell
Classic Locality
Huaron Tetrahedrite
Cu12Sb4S13 | Cubic I-43m
Mohs 3.8 | SG 4.95
Sharp mirror {111} triangles; zero cleavage; black streak
Huaron, Pasco Peru
Tsumeb Tennantite
Cu12As4S13 | Cubic I-43m
Mohs 4.2 | SG 4.65
As-rich; modified bevels; dark cherry-brown streak
Tsumeb, Namibia
Silver Freibergite
(Ag,Cu)12Sb4S13
Mohs 3.5 | SG 5.20
Up to ~30% Silver! Brighter pewter metallic sheen
Freiberg / Yukon
Chalco-Rimmed Fahlore
Cu12Sb4S13 + CuFeS2
Epitaxial Gold Trim
Natural brassy Chalcopyrite plates along bevel edges
Baia Sprie / Peru
Enargite Blades
Cu3AsS4 | Orthorhombic
Mohs 3.0 | Striated!
Ribbed oblong prisms with crisp side cleavages
Quiruvilca / Montana
Blackjack Sphalerite
(Zn,Fe)S | Cubic
Mohs 3.8 | SG 4.05
Same triangles — 6-way cleavage & pale tan streak
Lookalike Control
Frequently Asked Mineralogy Questions
Collector & Lab Answers
What is the chemical difference between Tetrahedrite and Tennantite?
They are endmembers of the exact same Fahlore sulfosalt solid-solution series: Tetrahedrite (Cu12Sb4S13) is Antimony-dominant (Sb), whereas Tennantite (Cu12As4S13) substitutes Arsenic (As) seamlessly into the Antimony sites.
How do you separate mirror-black Tetrahedrite from lookalike Black Sphalerite?
Look closely at broken edges and run a streak test: Black Sphalerite shows flat shiny 6-direction cleavage planes and draws a pale yellow-brown streak, while Tetrahedrite has zero cleavage (glassy conchoidal fracture) and leaves a dark grey-black to cherry-black streak.
Why do some Tetrahedrite crystals have golden brass borders along their edges?
During final pocket cooling, matching sulfur atomic grids allowed golden Chalcopyrite (CuFeS2) to grow epitaxially right over reactive bevel edges of the dark Tetrahedrite crystals—creating natural metallic 'gilded' rims.
What is Freibergite and why did medieval miners prize Fahlore?
Freibergite is Silver-rich Tetrahedrite where Silver atoms replace Copper inside the crystal cage (up to 30+ wt% Ag), serving as one of Europe's and the Andes' richest silver ores.
Are Tetrahedrite and Tennantite safe to handle bare-handed?
Solid display crystals are stable indoors, yet because they pack concentrated Antimony, Copper, and Arsenic, always wash hands thoroughly with soap and water afterward and never grind, scratch, or heat sulfosalts.