GEM KNOWLEDGE · LABORATORY NOTES
Sumatran Agate
Two banded specimens sold as Sumatran Agate were examined. Both tested as quartz in its chalcedony/agate form.
Tested specimens: Sample 1506 (#4 Sumatran agate) · Report completed: June 23, 2025.
Key finding: Red bands contained 0.2–0.8 wt.% iron, while the white-gray bands had no quantifiable iron in the tested areas. Black bands contained up to 0.3 wt.% manganese.
What the bands reveal
The report confirms the quartz/chalcedony identity of both specimens and documents chemical differences between their colored bands. These measurements describe the tested spots; they do not by themselves identify a precise pigment mineral or independently verify geographic origin.
View the original test results
Select any page to enlarge the full laboratory report.
The report applies to these specimens. Please credit Soul Body Gems, Alexander Falster, and the Maine Mineral & Gem Museum when referring to the results.
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 image of an area of the specimen in Fig. 1. (top)
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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 spectrum of spot 1 in Fig. 2. (quartz)
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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 spectrum of spot 2 in Fig. 2. (quartz)
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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 image of an area of the specimen in Fig. 1. (bottom)
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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 spectrum of spot 1 in Fig. 5. (quartz)
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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 spectrum of spot 2 in Fig. 5. (quartz)
Read the report findings as text
Sample 1506 (#4 Sumatran agate), completed June 23, 2025. SEM and XRF examination found both specimens to be quartz (chalcedony/agate). The red bands contained 0.2–0.8 weight percent iron; white-gray bands contained no quantifiable iron. Black bands contained up to 0.3 weight percent manganese. Figures 1–7 show specimen photographs, backscattered electron images, and energy-dispersive spectra of quartz spots.
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: 1506 (#4 Sumatran agate)
Submitted by: Soul Body Gems
Date completed: 6-23-2025
Operating conditions: An AMRAY 1830 SEM operated at 25 kV acceleration potential, 24 mm working distance, 0 degrees sample tilt, coated with 250 Å carbon, and also using the attached XRF unit operated at 30 kV.
Fig. 1: Photograph of the specimens. 6.5 cm maximum dimension.
Fig.2: Backscattered electron image of an area of the specimen in Fig. 1. (top)
Fig. 3: Energy dispersive spectrum of spot 1 in Fig. 2. (quartz)
Fig. 4: Energy dispersive spectrum of spot 2 in Fig. 2. (quartz)
Fig.5: Backscattered electron image of an area of the specimen in Fig. 1. (bottom)
Fig. 6: Energy dispersive spectrum of spot 1 in Fig. 5. (quartz)
Fig. 7: Energy dispersive spectrum of spot 2 in Fig. 5. (quartz)
Summary of findings: These are interesting specimens (Fig. 1). Both are quartz (chalcedony/agate (Figs. 2-7).
The red bands contain 0.2-0.8 wt. % iron, the white gray ones do not contain quantifiable amounts of iron. The black bands contain up to 0.3 wt. % of manganese.
Date: 6-23-2025 Signature