GEM KNOWLEDGE · LABORATORY NOTES
Specular Hematite (Ukraine)
A Ukrainian specimen of sparkling specular hematite shows the geological story of a metamorphosed banded iron formation.
Finding: Sample 92932 (#17), completed August 2, 2022, contains coarser crystalline hematite with specular luster, bands of quartz, some magnetite and a calcium-bearing amphibole or related pyroxene.
The laboratory describes formerly earthy hematite recrystallizing during metamorphism. This entry is specifically labeled Ukraine because specular hematite occurs in multiple localities; the result applies to this Ukrainian specimen.
View the original report
Select a page to enlarge it. 4 pages; findings are summarized in accessible text above.
Report images © Soul Body Gems, Alexander Falster and the Maine Mineral & Gem Museum. Please acknowledge all three when referring to these results. Findings apply to the specimen examined.
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 spectral analysis of the area shown in Fig. 2 (hematite/magnetite)
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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 the area shown 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. 5: Energy dispersive spectral analysis of the area shown in Fig. 2 (tremolite-actinolite series, could also be the pyroxene analogue)
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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. 6: X-ray map of the area shown in Fig. 2. Silicon: red, iron: green, calcium: blue.
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: 92932 (#17, specular hematite from Ukraine)
Submitted by: K. Bitner
Date submitted: July 14, 2022.
Date completed: Aug. 2, 2022.
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 D2 Phaser X-ray diffractometer was used and operated at 30 kV and 10 mA.
Fig. 1: Photograph of the specimen. Approximately 5 cm across
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Fig. 2: Backscattered electron image of an area of the specimen.
Fig. 3: Energy dispersive spectral analysis of the area shown in Fig. 2 (hematite/magnetite)
Fig. 4: Energy dispersive spectral analysis of the area shown in Fig. 2 (quartz)
Fig. 5: Energy dispersive spectral analysis of the area shown in Fig. 2 (tremolite-actinolite series, could also be the pyroxene analogue)
Fig. 6: X-ray map of the area shown in Fig. 2. Silicon: red, iron: green, calcium: blue.
Table 1: Minor and trace element composition of the specimen. (in wt. %).
| Element | Reported value |
|---|---|
| Aluminum | 0.24 |
| Calcium | 2.44 |
| Chromium | 0.02 |
| Cobalt | 0.15 |
| Manganese | 0.05 |
| Magnesium | 1.11 |
| Phosphorus | 0.02 |
| Vanadium | 0.11 |
Summary of findings: This specimen (Fig. 1) is a very nice example of metamorphosed banded iron formation. The initially red, earthy hematite has become coarser crystalline and has now the luster of specular hematite (Figs. 2 and 3). Bands of quartz (Figs. 2 and 4) are typical. Some magnetite has also formed during the metamorphism. Some tremolite-actinolite (Figs. 2 and 5) or its pyroxene equivalents are also present. This composition resembles a lot the Proterozoic banded iron formations of the Great Lakes region for example. There also, some have been affected by metamorphism which produced specular hematite plus some magnetite. Very high metamorphism may result in pure hematite/magnetite deposits sich as the Champion mine in Marquette Co., Michigan.
Date: Aug. 2, 2022 Signature