GEM KNOWLEDGE · LABORATORY NOTES
Maligano Jasper (Indonesia)
Maligano Jasper is a distinctive market name associated with material supplied from Indonesia. The tested mineral assembly differs from what the word “jasper” might imply.
Finding: This specimen has a white-to-tan magnesite matrix cut by veins made predominantly of dolomite, with minor pyrite. X-ray diffraction was used to confirm magnesite rather than hydromagnesite or another magnesium-bearing phase. The report does not identify it as quartz-rich jasper.
The researcher suggested the material may reflect low-temperature metamorphic effects on ultramafic rocks; that geological history is a possibility, not a proven origin for all material sold under the name.
Tested specimen: Sample 92962 (#5), approximately 5.5 cm across; report completed April 13, 2023. Indonesia is the supplied locality, not a mine of origin established by the analysis.
View the original report
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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 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. 3: Energy dispersive spectral analysis of spot 1 in Fig. 2. (magnesite?).
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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. (magnesite?).
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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 3 in Fig. 2. (dolomite).
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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 4 in Fig. 2. (pyrite).
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Diffraction scan: This scan helps identify crystalline minerals by comparing the measured pattern with reference patterns. The laboratory interpretation explains which minerals the comparison supports.
Laboratory figure caption: Fig. 7: X-ray diffraction scan of the high-magnesium material
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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. 8: X-ray map of magnesium (red), calcium (blue), iron (green).
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: 92962 (#5)
Submitted by: K. Bitner
Date submitted: March 23, 2023.
Date completed: April 13, 2023.
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.
A Bruker Titan X-ray fluorescence spectrometer was also used and operated with 50, 25 and 10 kV.
A Bruker D2 Phser X-ray diffractometer was used and operated at 30 kV voltage and 10 mA current.
Fig. 1: Photograph of the specimen. Approximately 5.5 cm across.
Fig. 2 Backscattered electron image of an area of the specimen shown in Fig.1.
Fig. 3: Energy dispersive spectral analysis of spot 1 in Fig. 2. (magnesite?).
Fig. 4: Energy dispersive spectral analysis of spot 2 in Fig. 2. (magnesite?).
Fig. 5: Energy dispersive spectral analysis of spot 3 in Fig. 2. (dolomite).
Fig. 6: Energy dispersive spectral analysis of spot 4 in Fig. 2. (pyrite).
Fig. 7: X-ray diffraction scan of the high-magnesium material
Fig. 8: X-ray map of magnesium (red), calcium (blue), iron (green).
Table 1: Minor and trace element composition of the high- magnesium area of the specimen. (in wt. %).
| Element | Reported value |
|---|---|
| Calcium | 0.40 |
| Iron | 0.21 |
| Manganese | 0.01 |
| Sulfur | 0.01 |
| Titanium | 0.02 |
Summary:
This is a very interesting specimen (Fig. 1). The specimen is composed of a white to tan matrix with some veins cutting through. The tan to white material is magnesite (Figs. 2,3, 4, 7 and 8), the veins are made up of dominantly dolomite *Figs. 2 and 5) with minor pyrite (Figs. 2 and 6). The magnesite is chemically pretty clean (table 1). This is material that may stem from low temperature metamorphic effects on ultramafic rocks. The X-ray diffraction scan was run to make certain the magnesium species is indeed magnesite and not hydromagnesite or others.
Date: April 13, 2023 Signature
