Carlsonite

carlsonite

anhydrite

boussingaultite

lonecreekite

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Formula: (NH₄)₅Fe³⁺₃O(SO₄)₆.7H₂O
Hydrated sulphate
Crystal System: Triclinic
Specific gravity: 2.167 calculated
Hardness: 2
Streak: Tan
Colour: Yellow to orange-brown
Luminescence: No fluorescence observed under UV
Solubility: Easily soluble in water at room temperature
Environments

Shale fire

Carlsonite is a relatively new mineral, approved in 2014 and to date (September 2024) reliably identified only from the type locality.

Localities

At the type locality, the Huron Shale burn site, Huron River, Huron County, Ohio, USA, the new minerals carlsonite and huizingite-(Al) formed from a natural fire in an oil-bearing shale. Carlsonite crystals are yellow to orange-brown thick tablets, or stout prisms, up to about 0.5 mm in size. It may be a more commonly formed mineral than its abundance would indicate and that its rarity may reflect a narrow stability range, and so a transitory existence (AM 101.9.2095-2107).
Associated minerals include anhydrite, boussingaultite, gypsum and lonecreekite (HOM).

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