DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS294

MINERAL_TYPE: Inosilicate

MINERAL: Cummingtonite (Amphibole group)

FORMULA: (Mg,Fe+2)7Si8O22(OH)2

FORMULA_HTML: (Mg,Fe⁺²)₇Si₈O₂₂(OH)₂

COLLECTION_LOCALITY: Lead, SD

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms series with Magnesiocummingtonite and Grunerite.

"I-13 Cummingtonite 294B--Lead, S. Dakota. (Mg, Fe²⁺)₅(Si₈O₂₂)(OH)₂: This amphibole has the same composition as anthophyllite, but is monoclinic rather than orthorhombic in crystal form. Its spectrum is a relatively smooth curve in which there is no evidence of hydroxyl bands, but in which the main feature is a broad ferrous iron band near 1.0µ. The lack of hydroxyl bands in what appears to be a rather pure amphibole in hand specimen is something that we cannot explain. Reflectivities I through IV are 40%, 24%, 12%, and 8% at 0.75µ, and 32%, 15%, 6%, and 4% at 1.0µ. The sample is a dark greenish gray. The low reflectivities are a function of this sample darkness, not of contamination with opaques."

Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1973, Visible and near-infrared spectra of minerals and rocks: VI. Additional silicates. Modern Geology, v. 4, p. 85-106.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Cummingtonite + quartz + biotite + chlorite + others (Norma Vergo)

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Sample has two different amphiboles, one green and the other clear in about equal proportions. Sample also contains significant quartz and trace garnet? 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 1313 0.2-3.0µm 200

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

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