TITLE: Copiapite GDS21 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS21

MINERAL_TYPE: Sulfate

MINERAL: Copiapite (Copiapite group)

FORMULA: Fe+2(Fe+3)4(SO4)6(OH)2*20H2O

FORMULA_HTML: Fe+2Fe+34(SO4)6(OH)2•20H2O

COLLECTION_LOCALITY: Cyprus

ORIGINAL_DONOR: MIT Mineral Collection, Dave Sherman

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV (smear mount on quartz, copiapit.out);
40 kV - 30 mA, 7.3-9.5 keV (slurry onto quartz plate, copiapt2.out)
References: JCPDS #35-583, 29-714, 20-659, 19-394, 33-1472, 42-599, 27-77
Found: two members of the copiapite group; perhaps at least one additional phase

Comment: The original pattern (copiapit.out) was barren above 30 degrees; a second pattern showed little above 38 degrees but the strip chart revealed that some reflections at low 2 theta are doublets, indicating the presence of two phases having related structures. The intensity ratio is about 5:2. There are seven mineral species in the copiapite group. I have not succeeded in completely indexing the pattern, using the JCPDS data, so I don't know which copiapite species (or solid solutions) are present. EDA analysis (on the SEM) shows a aluminum and silicon in addition Fe, S, and O. This results could indicate that one of the copiapites is Al-rich. Also that a trace of quartz is present (there are what I call insignificant peaks at the positions of the strong quartz (100) and (101) reflections - insignificant because they could just as likely be background noise. A hand-specimen with crystals suitable for single- crystal X-ray diffraction would help us sort out the copiapite species present."

J.S. Huebner, J. Pickrell, and T. Schaefer, 1994, written communication.

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Yellow color, good rhombic(?) cleavage, inclined extinction, length fast, unable to get good interference figure because of preferred cleavage orientations. Trace pink transparent mineral. 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 1239 0.2-3.0µm 200 g.s. = 225 µm

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

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