GEM KNOWLEDGE · MATERIAL IDENTIFICATION
African Turquoise
A Nigerian blue material, two tested specimens, and a name that needed a closer look.
A beautiful blue stone can look like turquoise without being the mineral turquoise. That distinction mattered when a newly found material from Nigeria came to us under the turquoise name.
Two colors, two samples
Some pieces were pale blue; others were much more vivid. The color recalled robin’s egg blue turquoise, but appearance and a seller’s name could not establish the identification. We submitted a lighter piece and a vibrant blue piece for testing.
What the results showed
The lighter sample was described as quartz with magnesium, aluminum, chromium, copper, and clay-related impurities. The darker blue sample was reported as likely plancheite or chrysocolla associated with quartz. Neither result identified the tested material as turquoise. The darker result remains a tentative identification between the named possibilities, and we would not turn it into a definitive species claim.
These findings describe the two samples examined. Because the material varies, a result for one piece should not automatically be represented as an individual report for every piece from the find. When we describe comparable material, we distinguish that broader inference from a test performed on a specific specimen.
Why the name matters
Turquoise is a distinct hydrated copper aluminum phosphate mineral. Blue color by itself is not enough to identify it. The phrase “African turquoise” is often used as a trade name for other materials; it does not establish that a particular stone is turquoise, nor does it tell us the exact mineral composition of every stone sold under that name. The tested Nigerian examples are a case study in why we ask for evidence before adopting a mineral name.
We still find this material beautiful. An accurate description lets people appreciate it for what it is, with the testing limits made clear.
The analytical reports
The first two images are report 1518 for the blue palm stone; the next three are report 1515 for the lighter palm stone. Select a page to enlarge it.
1518 · Blue · 1/2
1518 · Blue · 2/2
1515 · Light green · 1/3
1515 · Light green · 2/3
1515 · Light green · 3/3
On a phone, swipe across to see all five report pages.
Reports reproduced as provided. The findings apply to the examined specimens.
Read both laboratory reports as text
The text below describes the five report images above, including the purpose and findings of their charts. Mineral identifications retain the analyst’s qualifications.
Blue palm stone — report 1518
Submitted by: Soul Body Gems. Completed: July 17, 2025.
Methods: AMRAY 1830 scanning electron microscope, 25 kV acceleration potential, 24 mm working distance, zero-degree sample tilt, 250 Å carbon coating; attached X-ray fluorescence unit at 30 kV. Bruker D2-Phaser X-ray diffractometer at 35 kV and 10 mA.
- Figure 1: Photograph of the blue palm stone.
- Figure 2: Backscattered electron image locating the two areas analyzed.
- Figures 3 and 4: Energy-dispersive spectra for spots 1 and 2, labeled chrysocolla in the report. The horizontal axis is X-ray energy in kiloelectronvolts; peaks are labeled by element. These charts show copper and silicon, with oxygen and magnesium also indicated. The analysis compares differently colored areas.
- Figure 5: X-ray diffraction scan with quartz and plancheite reference patterns. The horizontal axis is diffraction angle and the vertical axis is counts. The analyst identifies quartz and possible plancheite, with poor crystallinity and likely amorphous material. No cristobalite or tridymite peaks are reported.
Analyst’s findings: The specimen is likely plancheite or chrysocolla associated with quartz. Color intensity is likely related to differences in porosity, possibly combined with slightly higher magnesium content in the lighter portion. X-ray diffraction indicates quartz and possible plancheite. Both show poor crystallinity; some material is likely amorphous. Chrysocolla typically has very poor crystallinity. The material does not show peaks for cristobalite or tridymite.
Light green palm stone — report 1515
Submitted by: Soul Body Gems. Completed: July 12, 2025.
Methods: AMRAY 1830 scanning electron microscope, 25 kV acceleration potential, 24 mm working distance, zero-degree sample tilt, 250 Å carbon coating; attached X-ray fluorescence unit at 30 kV. Bruker D2-Phaser X-ray diffractometer at 35 kV and 10 mA.
- Figure 1: Photograph of the specimen, maximum dimension 5 cm.
- Figure 2: Backscattered electron image locating three analyzed spots.
- Figures 3–5: Energy-dispersive spectra, each labeled quartz with impurities. The horizontal axis is X-ray energy in kiloelectronvolts; peaks are labeled by element. Spot 1 contains aluminum, magnesium, chromium and copper. Spot 2 lacks aluminum and may be quartz with a little serpentine. Spot 3 has the highest quartz content.
- Figure 6: X-ray diffraction scan with a quartz reference pattern. The horizontal axis is diffraction angle and the vertical axis is counts. The pattern confirms quartz; a small additional mineral component is interpreted as likely a clay species.
Analyst’s findings: The specimen consists mainly of quartz. Its porous texture suggests a low-temperature origin, such as a fracture fill. It may previously have been common opal that later crystallized. Impurities include magnesium, aluminum, chromium and copper. The analyst suggests formation in fractures of an ultramafic rock or its altered equivalent; magnesium and chromium are typical indicators. Spot 2 may include a little serpentine. X-ray diffraction confirms quartz and a small amount of another mineral, likely a clay species.
These explanations convey the chart findings; numerical peak-by-peak data are not provided in the reports and have not been invented.
Report acknowledgment: These analytical results and report materials are the property of Soul Body Gems, Alexander Falster, and the Maine Mineral & Gem Museum. Any use or mention of these results requires full acknowledgment of all three.