358 - Goethite and Limonite

ID	358
Mineral	Goethite Limonite
Location	Nordrhein-Westfalen - Germany
Fluorescence	LW-UV: close SW-UV: close
Mindat.org	View Goethite information at mindat.org View Limonite information at mindat.org

ID	1719
Long ID	1:1:1719:6
Formula	`FeO(OH)`
IMA Status	0 1
Other Occurrences	Common weathering product, primary hydrothermal mineral, bog and marine environments.
Industrial	Iron ore
Discovery Year	1806
Diapheny	Opaque
Cleavage	{010}; {100} less perfect.
Tenacity	brittle
Colour	Brownish black, yellow-brown, reddish brown
Hardness (min)	5.0
Hardness (max)	5.5
About the name	Named in 1806 by Johann Georg Lenz in honor of the German poet, novelist, playwrighter, philosopher, politician, and geoscientist Johann Wolfgang von Goethe [August 28, 1749, Frankfurt, Germany – March 22, 1832, Weimar, Germany]. Goethe was Chief Minister of State of Weimar. (Portions of the Goethe mineral collection are reputedly held by the Goethe Society in New York, New York, USA.)
Streak	Yellowish brown, orange-yellow, ocher-yellow
Crystal System	Orthorhombic
Cleavage Type	Perfect
Fracture type	Irregular/Uneven
Morphology	Prismatic [001] and striated [001]; also flattened into tablets or scales on {010}. Velvety aggregates of capillary crystals to acicular [001] and long prismatic forms often radially grouped. Massive, reniform, botryoidal, stalactitic. Bladed or columnar. Compact or fibrous concretionary nodules. Oolitic.
Twinning	Apparently none reported, but see https://www.mindat.org/mesg-631125.html and compare twinning in isostructural diaspore.
Thermal Behaviour	Heated in a closed tube, gives off water.
shortcode_ima	Gth
Group	Diaspore Group

ID	2402
Long ID	1:1:2402:6
Description	Currently used as a field-term for unidentified massive hydroxides and oxides of iron, with no visible crystals, and a yellow-brown streak. 'Limonite' is most commonly the mineral species goethite, but can also consist of varying proportions of lepidoc...
Diapheny	Opaque
About the name	Named in 1813 by Johann Friedrich Ludwig Hausmann from the Greek λειμών for meadow alluding to its common occurrences in bogs.

Goethite and Limonite