GEM KNOWLEDGE · LABORATORY NOTES
Purple Aventurine
A purple to lilac-gray sphere marketed by some as Purple Aventurine was tested to determine its mineral composition.
Tested specimen: 92848 (#6) · Report completed: March 2, 2022
Key finding: The laboratory found it to be essentially monomineralic lepidolite. No detectable albite was seen in the mapped area, and the report notes no quartz in this specimen.
What the report means
The lilac-gray color was interpreted as likely related to iron, manganese, and titanium contents. A low potassium-to-rubidium ratio is consistent with an evolved granitic pegmatite. The laboratory describes this particular piece as essentially lepidolite, with no quartz or albite identified in the tested area. The “Purple Aventurine” label does not negate the lepidolite finding. See Lepidolite (Purple) for the companion entry.
View the original test results
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The images reproduce the laboratory report for the specimen named above.
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. (lepidolite)
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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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Element map: This map shows where the named elements occur within the analyzed area. Its colors represent the laboratory’s selected element channels, rather than the specimen’s visible colors. The caption below preserves any color key or distribution noted by the laboratory.
Laboratory figure caption: Fig. 5: X-ray maps of the area shown in Figs. 2 Potassium green, sodium red. Note that no detactable albite was seen in the image. Darker area at lower left is caused by the curvature of the sphere.
Read the report as text
This transcription makes the laboratory findings, figure captions, and table values available without opening the page images. Refer to the original images above for visual details.
Laboratory report
Analytical Result Report Sample id: 92848 (#6) Submitted by: K. Bitner Date submitted: Feb. 14, 2022. Date completed: March 2, 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. 5.5 cm maximum dimensions. Fig. 2: Backscattered electron images of the specimen. Fig. 3: Energy dispersive spectral analysis of spot 1 in Fig. 2. (lepidolite) Fig. 4: Energy dispersive spectral analysis of spot 2 in Fig. 2. (lepidolite) Fig. 5: X-ray maps of the area shown in Figs. 2 Potassium green, sodium red. Note that no detactable albite was seen in the image. Darker area at lower left is caused by the curvature of the sphere. Table 1: Minor and trace element composition of the variscite portion of the specimen. (in wt. %). Iron 0.09 Manganese 0.06 Titanium 0.15 K/Rb ratio 11 Summary of findings: This specimen (Fig. 1) is essentially monomineralic lepidolite (Figs. 2-5). It is very common in pegmatitic lepidolite masses to see some albite and/or quartz but not in this case. The color is also interesting, this lilac- gray is likely a result of relatively similar contents of iron, manganese, and titanium and the resulting intervalence charge transfer reactions are probably responsible for the color. Higher manganese would result in more intense purple colors. The low K/Rb ratio is typical for geochemically evolved granitic pegmatites. Date: March 2, 2022 Signature