Jacobsite
A variety of Minerals
What is Jacobsite?
Jacobsite is a manganese iron oxide mineral. It is in the spinel group and forms a solid solution series with magnetite. The chemical formula is MnFe2O4 or with oxidation states and substitutions: (Mn,Fe,Mg)(Fe,Mn)2O4. It occurs as a primary phase or as alteration of other manganese minerals during metamorphism of manganese deposits. Typical associated minerals include hausmannite, galaxite, braunite, pyrolusite, coronadite, hematite and magnetite. It is a ferrimagnetic substance, which is weakly attracted by a magnet. It was first described in 1869 and named for the Jakobsberg Mine, Nordmark, Filipstad, Värmland, Sweden.
Optical Properties
- Optical Character
- Isotropic
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Jacobsite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Jacobsite Localities Map
See where Jacobsite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
More Images
Quick Facts
Physical Properties
- Color
- Black, gray in reflected light
- Hardness (Mohs)
- 5.5 - 6.5
- Density
- 5.03 g/cm³
- Streak
- Reddish black
Chemical Properties
- Chemical Formula
- Mn2+Fe3+2O4
- Elements
- Fe, Mn, O
Identify Jacobsite Instantly
- Snap a photo, get instant results
- 6,700+ rocks, minerals & crystals
- Discover collecting spots near you
Jacobsite FAQs
How do I identify Jacobsite?
Jacobsite can be identified by its hardness of 5.5 - 6.5 on the Mohs scale, Black color. Look for these key characteristics when examining specimens.
What color is Jacobsite?
Jacobsite typically appears in Black, gray in reflected light. Color can vary depending on impurities and formation conditions.
How hard is Jacobsite?
Jacobsite has a hardness of 5.5 - 6.5 on the Mohs scale. This gives it moderate hardness.
%252FAbenakiite-(ce)-01.jpg&size=small)
