TITLE: Goethite WS219 (Limonite) DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: WS219

MINERAL_TYPE: Hydroxide

MINERAL: Goethite

FORMULA: alpha-FeO(OH)

FORMULA_HTML: alpha-FeO(OH)

COLLECTION_LOCALITY: Tuscaloosa, Alabama

ORIGINAL_DONOR: Wards Natural Science Inc.

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Polymorphous with Akaganeite, Feroxyhyte, and Lepidocrocite.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

None.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

None.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

mode:
50 vol% limonite coated quartz grains
35 vol% limonite small grains & limonite coated quartz
15 vol% limonite large grains

bimodal grain size distribution:
mode 1: av gr sz limonite coating = 8 µm 30 vol%
mode 2: av gr sz limonite grains = 60 µm 15 vol%

av gr sz = 35 µm of limonite

Smaller limonite grains 80% coat larger limonite and quartz grains. Grains size too small or grains isotropic so I cannot determine optical properties. In plain light grains resemble plates and not fibres suggesting the possible dominance of lepidochrosite? Yellow-brown color and high relief. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1_2_3_4_

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment

LIB_SPECTRA: splib04a r 1802 0.2-3.0µm 200 g.s.= 35 µm

LIB_SPECTRA: splib05a r ____ 0.2-3.0µm 200 g.s.=

LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=