Comparison · Carbonates vs Sulfide Minerals
Siderite vs Sphalerite
Siderite and Sphalerite are easy to confuse. Both sit near Mohs 4, 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 Siderite and Sphalerite
- Both sit near Mohs 4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Siderite leaves a white streak on unglazed porcelain, Sphalerite leaves brownish white to pale yellow.
- Luster is different: Siderite is vitreous while Sphalerite is resinous.
- Hold a thin edge to the light: Siderite is translucent, Sphalerite is transparent.
- They overlap in brown and yellow, but Siderite also comes in gray and Sphalerite also comes in black, red, and green.
- Well-formed crystals give it away: Siderite is trigonal, Sphalerite is cubic.
Siderite vs Sphalerite properties
| Property | Siderite | Sphalerite |
|---|---|---|
| Type | Carbonates | Sulfide Minerals |
| Mohs hardness | 4 | 3.75 |
| Luster | vitreous | resinous |
| Streak | White | Brownish white to pale yellow |
| Transparency | translucent | transparent |
| Specific gravity | 3.96 | 4.05 |
| Crystal system | trigonal | cubic |
| Common colors | Yellowish brown, Brown, Tan, Gray | Brown, Black, Yellow, Red, Green |
| Rarity | common | common |
| Typical specimen value | $5–$350+ | $5–$600+ |
Which is more valuable?
Sphalerite is usually the more valuable of the two: a typical collector specimen runs about $70 against $45 for Siderite, and premium Sphalerite can reach $600 or more.
About Siderite
Siderite is an iron carbonate mineral that occurs as honey-brown to tan rhombohedral crystals, often with curved or saddle-shaped faces. It also forms massive and concretionary masses and is a recognized iron ore.
About Sphalerite
Sphalerite is zinc sulfide, the most important ore of zinc. It ranges from honey-yellow and green to brown and black, with a distinctive resinous to adamantine luster and perfect dodecahedral cleavage in six directions.
Siderite vs Sphalerite FAQ
Is Siderite the same as Sphalerite?
No. Siderite is a carbonate while Sphalerite is a sulfide mineral. Both sit near Mohs 4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Siderite from Sphalerite?
Both sit near Mohs 4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Siderite leaves a white streak on unglazed porcelain, Sphalerite leaves brownish white to pale yellow. Luster is different: Siderite is vitreous while Sphalerite is resinous.
Which is harder, Siderite or Sphalerite?
They are about equally hard, both near Mohs 4.
Which is more valuable, Siderite or Sphalerite?
Sphalerite is usually the more valuable of the two: a typical collector specimen runs about $70 against $45 for Siderite, and premium Sphalerite can reach $600 or more.
