Natrojarosite is a secondary mineral commonly found in the oxidized zones of metal-rich sulfide deposits. It typically forms as bright yellow earthy crusts or powdery masses that are easily mistaken for jarosite or limonite.
Is this natrojarosite?
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 natrojarosite with a known reference. Natrojarosite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow, ochre yellow, ochre brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: crystalline, fibrous, massive.
Often confused with
Natrojarosite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Natrojarosite leaves light yellow, Jarosite leaves pale yellow; luster reads vitreous on Natrojarosite and subadamantine to vitreous, resinous on fractures on Jarosite.
How to tell apart: Goethite is the harder of the two (Mohs 5-5.5 vs. 3); streak differs, so Natrojarosite leaves light yellow, Goethite leaves brownish yellow, yellow-orange, ocher-yellow; luster reads vitreous on Natrojarosite and imperfect adamantine metallic to dull earthy; silky when fibrous on Goethite.
How to tell apart: Limonite is the harder of the two (Mohs 4-5.5 vs. 3); streak differs, so Natrojarosite leaves light yellow, Limonite leaves yellowish-brown; luster reads vitreous on Natrojarosite and submetallic to earthy on Limonite.
Often found alongside natrojarosite
Minerals reported to co-occur with natrojarosite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaFe₃(SO₄)₂(OH)₆
- Mohs hardness
- 3
- Density
- 3.11-3.18 g/cm³
- Colors
- Streak
- Light yellow
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Trigonal
- Crystal habit
- Crystalline, fibrous, massive
- Cleavage
- Perfect on {0001}
- Rarity
- Common
- Uses
- Collector, Research
- Host rock
- Formed typically in the oxidized zone of mineral deposits by alteration of pyrite in the presence of sodium; rarely as a volcanic sublimate
Where rockhounds find natrojarosite
Classic worldwide localities
- East side of Soda Springs Valley, Mineral Co., and at Gilbert, 40 km east of Mina, Esmeralda Co., Nevada, USA
- Cook’s Peak, Luna Co., New Mexico, USA
- Georgia Sunset claim, about 6 km south of Kingman, Mohave Co., Arizona, USA
- Tintic district, Juab Co., Utah, USA
- Rapid Creek, Yukon Territory, Canada
- San Toy mine, Santa Eulalia, Chihuahua, Mexico
Field-hunting tip
Where it forms: Formed typically in the oxidized zone of mineral deposits by alteration of pyrite in the presence of sodium; rarely as a volcanic sublimate. If you start seeing gypsum, alunite, jarosite in float, you are in the right ground. Typical habit: crystalline, fibrous, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify natrojarosite?+
Where is natrojarosite found?+
What rocks look like natrojarosite?+
What minerals are found with natrojarosite?+
What kind of rock does natrojarosite form in?+
What is natrojarosite used for?+
Find natrojarosite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
