GEM KNOWLEDGE · LABORATORY NOTES
Star Citrine
A natural citrine sphere with a remarkable twelve-rayed asterism.
What the report found: Quartz with microscopic rutile needles; the observed star has twelve rays.
The approximately 23.8 mm sphere was sourced as a Madagascar specimen. The laboratory identified quartz and microscopic rutile needles; the specimen shows a striking 12-rayed star. The report says the star is probably related to twinning of the quartz, and the rutile needles appear aligned perpendicular to the crystal's c-axis. The report describes it as a natural specimen.
The star is best seen when looking down the c-axis. Its full twelve rays are difficult to capture in the report photograph. The locality was supplied with the stone rather than established by the chemical analysis.
Same specimen: Star Citrine · Citrine (Madagascar)
View the original report
Select a page to enlarge it. A text transcript appears below.
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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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. 2: Energy dispersive spectrum of spot 1 in Fig. 2. (rutile)
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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 2 in Fig. 2. (quartz)
Read the report as text
Analytical Result Report
Sample id: 9189 (small citrine sphere)
Submitted by: K.Bitner
Date submitted: Sept. 9, 2020
Date completed: Sept. 15, 2020
Operating conditions: JEOL JSM-6400 operated at 25 kV acceleration potential, 15 mm working distance, 15 degrees
sample tilt, coated with 250 Å carbon. Using the X-ray fluorescence attachment with 35kv potental in conjunction with
the EDS system.
Fig. 1: Photograph of the sphere showing a beautiful 12-rayed asterism. Diameter of the sphere is 23.8 mm.
2
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1
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Fig. 3: close-up showing two thin rutile inclusions. Field of view is 600 microns.
Fig. 2: Energy dispersive spectrum of spot 1 in Fig. 2. (rutile)
Fig. 3: Energy dispersive spectrum of spot 2 in Fig. 2. (quartz)
Table 1: Trace element content of the sphere.
element concentration
Titanium 155 ppm
Aluminum 120 ppm
Iron 88 ppm
Summary of findings: This is an incredible specimen! The asterism shows a 12-rayed star (not easy to show all rays in
the photograph) which is probably related to twinning of the quartz crystal. The star is best viewed down the c-axis of
the crystal, the microscopic rutile inclusions appear to be aligned in a plane perpendicular to the c-axis. T was tricky to
find a rutile needle penetrating through the surface to get the chemistry determined. Only titanium, iron and aluminum
were detected in quantifiable amounts in the specimen. This is a natural specimen.
Date: September 15 ,2020 Signature