Marcobaldiite is a rare lead-antimony sulfosalt known primarily from its type locality in the Apuan Alps of Italy. It typically forms as dark, lead-black metallic tabular crystals found within hydrothermal vein deposits.
Is this marcobaldiite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch marcobaldiite with a known reference. Marcobaldiite sits at Mohs 3-3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals.
Often confused with
Marcobaldiite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Marcobaldiite leaves black, Galena leaves lead-gray.
How to tell apart: Streak differs, so Marcobaldiite leaves black, Jamesonite leaves black. grayish.
How to tell apart: Streak differs, so Marcobaldiite leaves black, Bournonite leaves steel-gray to iron-black; luster reads metallic on Marcobaldiite and brilliant to dull on Bournonite.
Often found alongside marcobaldiite
Minerals reported to co-occur with marcobaldiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₁₂(Sb₃As₂Bi)S₂₁
- Mohs hardness
- 3-3.5
- Density
- 6.56 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Triclinic
- Crystal habit
- Tabular crystals
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In quartz extension veins in a baryte+pyrite±(Pb-Zn-Ag) ore deposit within a metavolcanic-metasedimentary rock sequence, that was metamorphosed to greenschist facies
Where rockhounds find marcobaldiite
Classic worldwide localities
- Stanzone tunnel, Pollone mine, near Valdicastello Carducci, Pietrasanta, Apuan Alps, Tuscany, Italy
Field-hunting tip
Where it forms: In quartz extension veins in a baryte+pyrite±(Pb-Zn-Ag) ore deposit within a metavolcanic-metasedimentary rock sequence, that was metamorphosed to greenschist facies. If you start seeing sb-rich tennantite, quartz in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify marcobaldiite?+
Where is marcobaldiite found?+
Is marcobaldiite safe to handle?+
What rocks look like marcobaldiite?+
What minerals are found with marcobaldiite?+
What kind of rock does marcobaldiite form in?+
What is marcobaldiite used for?+
Find marcobaldiite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
