Hulsite is a rare tin-bearing borate mineral typically found in complex skarn deposits formed by contact metamorphism. It is characterized by its dark, submetallic appearance and is often difficult to distinguish from other minerals in the ludwigite-vonsenite series without chemical analysis.
Is this hulsite?
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 hulsite with a known reference. Hulsite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hulsite leaves a brownish-black streak.
- 3Read the lusterHold the specimen under a strong light. Hulsite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, massive, granular.
Often confused with
Hulsite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Ludwigite is the harder of the two (Mohs 5 vs. 3.5); streak differs — Hulsite leaves brownish-black, Ludwigite leaves black.
How to tell apart: Vonsenite is the harder of the two (Mohs 5 vs. 3.5); streak differs — Hulsite leaves brownish-black, Vonsenite leaves black.
Often found alongside hulsite
Minerals reported to co-occur with hulsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Fe²⁺,Mg,Sn⁴⁺,Fe³⁺,Ti)₃BO₆
- Mohs hardness
- 3.5
- Density
- 4.57 g/cm³
- Colors
- Streak
- Brownish-black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Massive, Granular
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Skarn
- Typical price
- $50-300 per specimen
Where rockhounds find hulsite
Classic worldwide localities
- Brooks Mountain, Alaska, USA
- Suan Mine, North Korea
- Yakutia, Russia
Field-hunting tip
Look in skarn country — that is the host setting where hulsite typically forms. If you start seeing magnetite, calcite, fluorite in float, you are in the right ground. Field specimens usually show a prismatic crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hulsite?+
Where is hulsite found?+
How much is hulsite worth?+
What rocks look like hulsite?+
What minerals are found with hulsite?+
What kind of rock does hulsite form in?+
What is hulsite used for?+
Find hulsite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
