Sanakirja
Tekoälykääntäjä
(mineralogy) A manganese iron oxide mineral, a magnetite spinel.
Jacobsite – General – Category – Oxide minerals – Spinel group – Spinel structural group – Formula – Iron(II,III) manganese oxide, (Mn,Mg)Fe₂O₄ – IMA symbol – Jcb – Strunz classification – 4.BB.05 – Crystal system – Isometric – Crystal class – Hexoctahedral (m̅3m) – H-M symbol: (4/m m̅3 2/m) – Space group – Fd̅3m (no. 227) – Unit cell – A = 8.457 Å; Z = 8 – Identification – Color – Black to brownish black – Crystal habit – Disseminated to massive, rarely as octahedral crystals – Twinning – Spinel law, flattened on {111} or lamellar – Cleavage – {111}, probably a parting – Fracture – Conchoidal – Mohs scale hardness – 5.5–6.5 – Luster – Metallic – Streak – Reddish black to brown – Diaphaneity – Opaque – Specific gravity – 4.76 – Optical properties – Isotropic – Refractive index – ~2.3 – Other characteristics – Weakly magnetic.
(mineralogy) A manganese iron oxide mineral, a magnetite spinel.
Jacobsite, N'Chwaning Mines, Kuruman, Kalahari manganese fields, Northern Cape Province, South Africa. Size 3.8 x 3.5 x 3.2 cm