Clark and others 2007 USGS Data Series 231
Spectral Library splib06a Sample Description

(For further information on spectroscopy, see: http://speclab.cr.usgs.gov)

TITLE: Psilomelane HS139 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS139

MINERAL_TYPE: Hydroxide (Mineral mixture)

MINERAL: Psilomelane (Romanechite)

FORMULA: BaMn+2(Mn+4)8O16(OH)4

FORMULA_HTML: BaMn⁺²Mn⁺⁴₈O₁₆(OH)₄

COLLECTION_LOCALITY: Magdalena, New Mexico

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

"0-13. Psilomelane. Magdalena, N.M. (139B). "Psilomelane" is generally used as a field term for any poorly characterized massive ore of manganese. Much of the material originally cleared as psilomelane consists of mixtures of several different minerals, usually with pyrolusite (Palache and others, 1944). Psilomelane usually is of supergene origin, occurring typically as a weathering product of manganiferous carbonates or silicates. This particular sample has a black streak, and yields very little water (0.09%) when heated. Consequently, we conclude that it is composed in large part of pyrolusite. Its spectrum is opaque and spectrally featureless, due to the conduction band of MnO₂ extending throughout this spectral range."

Sieve interval 74 - 250µm.

Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1971, Visible and near-infrared spectra of minerals and rocks: III. Oxides and hydroxides. Modern Geology, v. 2, p. 195-205.

"Many of the hard botryoidal masses formerly called psilomelane are now known to be a mixture of several manganese oxides of which romanechite is a major constituent. Some of the other minerals commonly present in the mixture are cryptomelane, KMn₈,O₁₆; manjiroite, (Na,K)Mn₈O₁₆^.nH₂O; and todorokite (Mn,Ca,Mg) Mn₃O₇^.H₂O."

Klein, C. and Hurlbut, C.S., Manual of Mineralogy 20th Edition, pp 317-318, 1985.

IMAGE_OF_SAMPLE:

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.0-9.5 keV
File: psilm139.mdi (smear on quartz plate)
References: PDF2 #14-0627
Found: Romanechite

Comments: All peaks are weak, most peaks broad, and the alpha1-alpha2 components are not resolved. The pattern has high background, probably due to Mn or Fe X-ray fluorescence. Within the range covered by the PDF2 data, all observed reflections were indexable as romanechite. There are some differences in intensity, however. The PDF2 lists additional reflections which were not observed in our poor pattern.

Romanechite (Major), Akhtenskite(Minor)..Sutley April, 2005

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2b3b4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

LIB_SPECTRA_HED:	where	Wave Range	Av_Rs_Pwr	Comment
LIB_SPECTRA:	splib04a r 3989	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib05a r 5635	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib06a r 18495			g.s.=
LIB_SPECTRA:	splib06a r 18507			g.s.=