GEM KNOWLEDGE · LABORATORY NOTES
Spinel on Marble (Pakistan)
Green spinel in calcite marble from Pakistan.
Sample 1088 (#16) · September 30, 2024.
Identification: spinel in calcite marble with minor magnesium.
What the testing revealed
The report attributes the spinel’s green color to chromium and iron. Minor zinc indicates a small gahnite component. The locality is based on Soul Body Gems sourcing information.
Spinel on Marble — sample 1088
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.
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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. (spinel)
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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 (calcite with minor magnesium content)
Read the complete report as text
Analytical Result Report
Sample id: 1088 (#16, Pakistani marble and spinel)
Submitted by: Soul Body Gems
Date completed: 9-30-2024
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 specimen. Approximately 45mm maximum dimension.
Fig.2: Backscattered electron image of an area of the specimen.
Fig. 3: Energy dispersive spectrum of spot 1 in Fig. 2. (spinel)
Fig. 4: Energy dispersive spectrum of spot 2 in Fig. 2 (calcite with minor magnesium content)
Table 1: minor and trace elements in the spinel, in wt. %
| Element | Reported value |
|---|---|
| Calcium | 0.55 |
| Chromium | 0.79 |
| Iron | 2.85 |
| Manganese | nd |
| Zinc | 0.45 |
Summary of findings: This specimen (Fig. 1) is beautiful! Spinel (Figs. 2 and 3) in marble (Figs. 2 and 4). The green color in the spinel is a result of chromium content as well as of iron content. Interesting to note is a small zinc content which indicates a small contribution of gahnite, the zinc spinel (Table 1). The marble has a small magnesium content (Fig. 4).
Date: 9-30-2024 Signature
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: 1088 (#16, Pakistani marble and spinel)
Submitted by: Soul Body Gems
Date completed: 9-30-2024
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 specimen. Approximately 45mm maximum dimension.
Fig.2: Backscattered electron image of an area of the specimen.
Fig. 3: Energy dispersive spectrum of spot 1 in Fig. 2. (spinel)
Fig. 4: Energy dispersive spectrum of spot 2 in Fig. 2 (calcite with minor magnesium content)
Table 1: minor and trace elements in the spinel, in wt. %
| Element | Reported value |
|---|---|
| Calcium | 0.55 |
| Chromium | 0.79 |
| Iron | 2.85 |
| Manganese | nd |
| Zinc | 0.45 |
Summary of findings: This specimen (Fig. 1) is beautiful! Spinel (Figs. 2 and 3) in marble (Figs. 2 and 4). The green color in the spinel is a result of chromium content as well as of iron content. Interesting to note is a small zinc content which indicates a small contribution of gahnite, the zinc spinel (Table 1). The marble has a small magnesium content (Fig. 4).
Date: 9-30-2024 Signature