GEM KNOWLEDGE · LABORATORY NOTES
Lepidocrocite in Quartz — Market Label
“Lepidocrocite in quartz” is a familiar sales label for red inclusions, but appearance does not establish the mineral species.
Finding for our specimen: Sample 92913 (#13) showed iron-oxide inclusions in clear quartz. The laboratory favored hematite based on observed structure; it did not conclusively identify hematite or demonstrate that lepidocrocite is absent. Destructive X-ray diffraction was not carried out.
Mindat states that red inclusions in many quartz crystals sold as lepidocrocite are normally hematite. The names are distinct mineral species, so we avoid treating them as interchangeable. This specimen illustrates why a market name should be checked rather than assumed.
Mindat · Lepidocrocite mineral information · See the main specimen entry
View the original report
Select a page to enlarge it. 3 pages; findings are summarized in accessible text above.
Report images © Soul Body Gems, Alexander Falster and the Maine Mineral & Gem Museum. Please acknowledge all three when referring to these results. Findings apply to the specimen examined.
Understanding the report figures
Use this guide alongside the written findings and the original report transcript. It explains the purpose of each analytical figure and preserves the laboratory’s own figure labels. The interpretations apply to the tested specimen; signals alone do not establish the identity of every similar-looking stone.
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Electron microscope image: This view shows small-scale regions selected for analysis. Its brightness contrast helps distinguish regions with different compositions; it is not a photograph of their natural colors. Numbered spots connect this view to the analyses listed in the report.
Laboratory figure caption: Fig. 3: Backscattered electron image of an area of the specimen shown in Fig.1.
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Elemental spectrum: The peaks record characteristic X-ray signals from elements in the analyzed spot or area. This is an analysis of that location, not automatically of the entire specimen. Any mineral identification or uncertainty named in the laboratory caption is retained below.
Laboratory figure caption: Fig. 4: Energy dispersive spectral analysis of spot 1 in Fig. 2 (iron oxide species)
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Elemental spectrum: The peaks record characteristic X-ray signals from elements in the analyzed spot or area. This is an analysis of that location, not automatically of the entire specimen. Any mineral identification or uncertainty named in the laboratory caption is retained below.
Laboratory figure caption: Fig. 5: Energy dispersive spectral analysis of spot 2 in Fig. 3 (quartz).
Read the original laboratory report as text
The following text and tables are transcribed from the original laboratory document. Figure captions identify the report images; the laboratory interpretations and limitations are preserved.
Laboratory report 1
Analytical Result Report
Sample id: 92913 (#13)
Submitted by: K. Bitner
Date submitted: July 14, 2022.
Date completed: September 9, 2022.
Operating conditions: An AMRAY 1830 SEM operated at 25 kV acceleration potential, 26 mm working distance, 15 degrees sample tilt, coated with 250 Å carbon. Using the X-ray fluorescence attachment with 35 kV potential in conjunction with the EDS system.
Fig. 1: Photograph of the specimen. Approximately 1.8 cm maximum dimension
Fig.2: Photomicrographs of the inclusions. Width of field approximately 2.5 mm.
Fig. 3: Backscattered electron image of an area of the specimen shown in Fig.1.
Fig. 4: Energy dispersive spectral analysis of spot 1 in Fig. 2 (iron oxide species)
Fig. 5: Energy dispersive spectral analysis of spot 2 in Fig. 3 (quartz).
Table 1: Minor and trace element composition of the specimen. (in wt. %).
| Element | Reported value |
|---|---|
| Aluminum | 0.1 |
| Iron | 0.4 |
Summary of findings: This specimen is interesting (Fig. 1). Bright red inclusions in clear quartz (Figs. 1, 2, 3 and 5). Compositionally, the inclusions are a clean iron oxide species (Figs. 3 and 4). The options are for the red inclusions either thin plates of hematite or lepidocrocite. The close-up in the right image in Fig. 3 has an arrow pointing at evidence of rhombohedral symmetry which would be typical for hematite whereas lepidocrocite is rhombohedral and would not show these offsets at the angle shown. This could be confirmed by X-ray diffraction but would require destroying the specimen.
Date: September 9, 2022 Signature