Comparison · Minerals
Chromite vs Franklinite
Chromite and Franklinite are easy to confuse because both are minerals. Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Chromite and Franklinite
- Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Chromite leaves a dark brown to black streak on unglazed porcelain, Franklinite leaves reddish brown to black.
- Both look metallic, so compare color, tarnish and weight rather than shine.
- Franklinite feels noticeably heavier for its size (specific gravity 5.1–5.2 versus 4.5–4.8 for Chromite).
Chromite vs Franklinite properties
| Property | Chromite | Franklinite |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 5.5 | 5.5–6.5 |
| Luster | Metallic to submetallic | Metallic to submetallic |
| Streak | Dark brown to black | Reddish brown to black |
| Transparency | Opaque | Opaque |
| Specific gravity | 4.5–4.8 | 5.1–5.2 |
| Crystal system | Isometric | Isometric |
| Common colors | Black, Brownish black | Black, Brownish black |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Chromite and Franklinite trade in a similar range, around $20.
About Chromite
Chromite is iron chromium oxide, FeCr2O4, a member of the spinel group and the only economically significant ore of chromium. It crystallizes in the cubic system as black to brownish-black grains or octahedral crystals, most often found disseminated through dark, dense mafic and ultramafic rocks. Its formation is closely tied to the early crystallization of magma in large layered igneous intrusions.
About Franklinite
Franklinite is a zinc iron manganese oxide, (Zn,Mn,Fe)(Fe,Mn)2O4, belonging to the spinel group and crystallizing in the isometric system, usually as black octahedral crystals or granular masses. It is virtually unique to the zinc deposits of Franklin and Sterling Hill, New Jersey, where it occurs in an assemblage found almost nowhere else on Earth. Though weakly magnetic, it is chemically distinct from true magnetite.
Chromite vs Franklinite FAQ
Is Chromite the same as Franklinite?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Chromite from Franklinite?
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Chromite leaves a dark brown to black streak on unglazed porcelain, Franklinite leaves reddish brown to black. Both look metallic, so compare color, tarnish and weight rather than shine.
Which is harder, Chromite or Franklinite?
Franklinite is harder: Mohs 5.5–6.5 against Mohs 5.5 for Chromite.
Which is more valuable, Chromite or Franklinite?
Typical specimens of Chromite and Franklinite trade in a similar range, around $20.
