Smythite is a rare iron sulfide mineral that typically forms as bronze to brownish platy crystals or granular masses. It is primarily found in sedimentary environments, notably within limestone and shale, and is physically quite similar to common pyrrhotite, often requiring laboratory identification to distinguish.
Is this smythite?
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 smythite with a known reference. Smythite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dark gray.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic; splendent on basal section.
- 4Match the color rangeCompare against the expected color range: brownish black, light bronze.
- 5Look at form & habitCrystal system: trigonal. Typical habit: hexagonal, platy, thin.
Often confused with
Smythite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside smythite
Minerals reported to co-occur with smythite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Fe,Ni)₉S₁₁
- Mohs hardness
- 4.5
- Density
- 4.32 g/cm³
- Colors
- Brownish blackLight bronze
- Streak
- Dark gray
- Luster
- Metallic; splendent on basal section
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Hexagonal, platy, thin
- Cleavage
- Perfect basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Formed as a low-temperature oxidation product of the strongly magnetic monoclinic phase of pyrrhotite, as inclusions in calcite crystals in quartz geodes; also in hydrothermal veins
Where rockhounds find smythite
Classic worldwide localities
- Monroe Co., Indiana, from a road cut about 3 km north of Bloomington (type locality), and near Unionville, USA
- Kramer borate deposit, Boron, Kern Co., California, USA
- Helena, Lewis and Clark Co., Montana, USA
- Silverfields mine, at Cobalt, and the Nicopor mine, north of Schreiber, Ontario, Canada
- Bird River mines, Lac du Bonnet area, Manitoba, Canada
- Manitoba, Canada
Field-hunting tip
Where it forms: Formed as a low-temperature oxidation product of the strongly magnetic monoclinic phase of pyrrhotite, as inclusions in calcite crystals in quartz geodes; also in hydrothermal veins. If you start seeing pyrite, greigite, mackinawite in float, you are in the right ground. Typical habit: hexagonal, platy, thin. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify smythite?+
Where is smythite found?+
Is smythite safe to handle?+
What rocks look like smythite?+
What minerals are found with smythite?+
What kind of rock does smythite form in?+
What is smythite used for?+
Find smythite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
