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Hulsite

Year of discovery: 1908 (Brooks mountain, USA), 2010 (Japan)

Locality list: A locality of hulsite

• Fe₃BO₅
• (Fe,Mg)₂(Fe,Sn)BO₅
• [Fe²⁺₂][Fe³⁺][O₂|BO₃]^7-

• Class: Borate - Oxide
• Soluble in: HCl, HNO₃ (Slightly), H₂SO₄ (Slightly), HF
• Alter to Limonite.

• Polymorph: Vonsenite (Orthorhombic)

• Fe => Mg: Magnesiohulsite, Ludwigite, Chestermanite, Azoproite
• Fe => Ni: Bonaccordite

• Color: Black
• Streak: Black
• Luster: Vitreous
• Diaphaneity: Opaque

• Cleavage: Good on {110} (2 planes)
• Hardness: 3
• Density: 4.3

• System: Monoclinic
• Group: 2/m, P2/m
• Lattice: a=10.7, b=3.1, c=5.4, β=94.2