GEM KNOWLEDGE · LABORATORY NOTES
Unicorn Lepidolite
Unicorn Lepidolite is our collection name for this lepidolite and tourmaline material. The name refers to the stone, rather than a unicorn-shaped carving.
The June sphere photograph is shown alongside the existing analysis of the raw specimen. The report identifies lepidolite, fluorapatite, albite and elbaite tourmaline in that submitted specimen; it does not measure every sphere pictured here.
A purple specimen supplied from Russia was tested to identify the mineral assemblage in its pegmatite.
Finding: Sample 92840 (#3), completed February 19, 2022, consists mainly of lepidolite with a low potassium-to-rubidium ratio. The purple color was attributed to manganese. The report also found a mass of fluorapatite, with albite and elbaite tourmaline near the tip.
The researcher interpreted the assemblage as an evolved granitic pegmatite. Russia is supplied provenance rather than a conclusion of the compositional testing.
View the original report
Select a page to enlarge it. 4 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. 2: Backscattered electron images of the specimen.
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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. 3: Energy dispersive spectral analysis of spot 1 in Fig. 2. (fluorapatite)
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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 2 in Fig. 2. (lepidolite)
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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. 5: Backscattered electron images of another area of the specimen.
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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. 6: Energy dispersive spectral analysis of spot 2 in Fig. 5. (albite)
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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. 7: Energy dispersive spectral analysis of spot 2 in Fig. 2. (elbaite tourmaline )
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: 92840 (#3)
Submitted by: K. Bitner
Date submitted: Feb. 14, 2022.
Date completed: Feb. 19, 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. 11.5 cm maximum dimension.
Fig. 2: Backscattered electron images of the specimen.
Fig. 3: Energy dispersive spectral analysis of spot 1 in Fig. 2. (fluorapatite)
Fig. 4: Energy dispersive spectral analysis of spot 2 in Fig. 2. (lepidolite)
Fig. 5: Backscattered electron images of another area of the specimen.
Fig. 6: Energy dispersive spectral analysis of spot 2 in Fig. 5. (albite)
Fig. 7: Energy dispersive spectral analysis of spot 2 in Fig. 2. (elbaite tourmaline )
Table 1: Minor and trace element composition of the specimen. (in wt. %).
| Element | Reported value |
|---|---|
| Iron | 0.07 |
| Titanium | 0.04 |
| Calcium | 0.14 |
| Manganese | 0.26 |
| Potassium/rubidium ratio | 12 |
Summary of findings: This specimen (Fig. 1) is a specimen from an evolved granitic pegmatite. The bulk is composed of lepidolite (Fig.2 and 4) with a low K/Rb ratio of 12 (Table 1) indicating high degree of geochemical evolution. The deep purple color is caused by manganese. A mass of fluorapatite is present as well (Figs. 2 and 3). Near the tip is some albite (Figs. 5 and 6) and elbaite (tourmaline group) (Figs. 5 and 7). Only evolved pegmatites produce this mineral assemblage!
Date: February 19, 2022 Signature
