Uvarovite

Spectrum Details

Modality

NIR

Category

mineral

Material Type

Nesosilicate

Sample ID

NMNH106661

Collection Locality

Unknown

Spectral Purity

1c2c3c4_ # NMNH106661 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

Composition / XRD

EPMA # XRF, EPMA, ICP(Trace), WChem

Sample Description

Forms series with Grossular. The garnet group includes a series of isostructural subspecies with space group Ia3d; the crystallize in the hexoctahedral class of the isometric system and are similar in crystal habit. Garnet compositions can be expressed by the general structural formula A3B2(SiO4) where the A site houses Ca, Mg, Fe^+2 or Mn^+2 and the B site incorporates Al, Fe^+3, and Cr+3. IMAGE_OF_SAMPLE:

XRD Analysis

40 kV - 30 mA, 6.5-9.5 keV File: uvarv106.out, *.mdi (smear mount on quartz plate) References: JCPDS #11-696, Huebner's reference patterns Found: garnet, talc, minor additional phase Comment: Talc based on three strong basal reflections. There were three unindexed reflections at 2.940, 2.510, and 1.495 Angstroms. The garnet has a=11.90 Angstroms, between that of uvarovite (12.00 Angstroms) or andradite (Angstroms) and grossular (11.85 Angstroms) or other garnet components with smaller cell dimensions. Based on the intense green color, this garnet contains significant uvarovite component, but the identity and proportions of other components is not known.

X Units

cm⁻¹

Y Units

Absorbance

Data Points

2,126