GEM KNOWLEDGE · LABORATORY NOTES
Blue Apatite Chert
A sphere where vivid blue apatite meets green and light brown chert.
What the report found: The blue portion is apatite; the green to light brown matrix is chert.
The sphere measures about 66 mm. The laboratory measured relatively modest iron and manganese in the blue area despite its saturated color and suggested that structural defects may enhance that blue. It associated the chert's green-to-brown color variation with different oxidation states of iron. The color mechanism in the apatite is presented as a likely explanation, not as a separately established cause for every blue apatite.
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.
-
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 spectral analysis of the blue area in Fig. 1.
Read the report as text
Analytical Result Report Sample id: 9194 (Blue Apatite) Submitted by: K.Bitner Date submitted: Sept. 9, 2020 Date completed: Sept. 16, 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 Apatite sphere. Maximum dimension is 66 mm. Fig. 2: Energy dispersive spectral analysis of the blue area in Fig. 1. Table 1: compositional results for the blue and green areas element Blue area Green area Iron 410 ppm 7.1 wt. % Sulfur 100 ppm 400 ppm Manganese 140 ppm 120 ppm Phosphorus 17.3 wt. % Not detected Silicon 1.22 wt. % 38.55 wt. % Calcium 39.2 wt. % 400 ppm Summary of findings: A very interesting specimen! Deep blue apatite (Figs 1-2 and Table 1) with greenish to light brown chert Fig. 1 and table 1). Despite the deep blue color, chromophoric trace elements such as iron and manganese are not very high. This something we have found in our work on apatite group species, the color intensity does not correlate well with chromophore concentrations. Thus, some defect in the structure likely enhances the color intensity. The cherty material and its color range from green to light brown is a result of the oxidation state of iron, divalent iron makes it green, trivalent makes it brown. Date: September 16 ,2020 Signature


