Arfvedsonite VS Astrophyllite

While the flashy appearance is similar, the chemical makeup is completely different. This is one of those cases of misinformation that spread from supplier to vendor to seller to customer. While both do have some acicular spraying (needle like crystals in a fan shape) that is where the comparison ends.

Arfvedsonite is one of those tumbles I see all over, often misidentified as Astrophyllite. Even after calling the wholesaler to provide them with accurate and updated information that they could use to correct their mistake, they never did.

Chemical Formula: [Na][Na2][Fe4 2+Fe3+]Si8O22(OH)2
Crystal System: Monoclinic
Hardness: 5-6
Group: Amphibole Group
Name: Named for Johan A. Arfvedson (Arfwedson) (1792-1841), Swedish chemist.

Astrophyllite, as you can see is more chocolate brown with golden copper acicular “needles” as opposed to Arfvedsonite’s dark brown/black matrix with blue and gold needles.

Chemical Formula: (K,Na)3(Fe,Mn)7Ti2Si8O24(O,OH)7
Crystal System: Triclinic
Hardness: 3
Group: Astrophyllite Group
Name: From the Greek “astron” for “star” and “phyllon” for “leaf”, in allusion to its habit of starburst-like sprays and micaceous cleavage.

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