Now that we have a "specimen-test table" we can now do cross comparisons of each of the chips examined in the paper. I aim to look at each characteristic in turn but to start with it makes sense to look at the Visual Characteristics, the "Gray Layer" and then the "Red Layer" for each sample as described in Fig 4.
Below are pictured the visual representations of 6 of the chips.
In observation we can clearly see that samples a, b, c and d match each other closely in characteristic. It is also plain to see that Fig 31 does not match any of the other chips. In addition it's "red layer" is far duller than that of the other chips and is sandwiched between the two darker grey, outside layers. None of the other chips exhibit these darker outer layers. Therefore we must conclude that this particular chip is significantly different and would not fit into the data set of chips a) to d). This chip should be examined and compared with samples a) to d) in order to find out why. If this comparison shows significant differences then we must conclude that the samples are from different materials or sources. If that is the case then this sample is not thermite.
Sample in Fig 13, "MEK chip" shows similarity in colour to samples a) to d) but there is no metallic "gray layer" shown nor is there a scale in order for comparison. Further on in the paper there is another optical photo of this particular chip and helpfully a SEM micrograph.
In the right hand image we can clearly see a "gray layer" but it is darker than that in samples a) to d) with no metallic reflection as seen in the "insert" in Fig 2d). We can say that this sample shares some general characteristics with samples a) to d), but further methods and analysis is required to confirm that they can be treated as one data set.
The left hand image is of the same sample with layers left to right comprising the "red layer" (which is post MEK testing therefore expanded), the "gray layer" and an unknown lighter fibrous appearing material. Now compare that sample with the SEM photo in Fig 4.
We can clearly see that the "gray layer" in Fig shows a sharp, crystalline and brittle layer. The "gray layer" in Fig 32 appears to have different characteristics. A higher SEM magnification should resolve whether this layer is identical to those in samples a) to d) but none is shown (which may well be due to space).
Note the possibility of a third layer in Fig 4 below and to the right of the roughly 90° corner in the "gray layer". Again this should be investigated because this may indicate other properties of the chip(s).
We also have images and data from a chip sent to a French investigator (and this will be referred to as to as the "French chip".
This French chip also shows three distinguishable layers with the third being of a crystalline fibrous appearance. The middle gray layer shares characteristics with both samples in Fig 4 and Fig 32. The paper states
Therefore we can see why Fig 32 and the French SEM photo differ from Fig 4 with respect to the "gray layer".
Whilst not conclusive we can say that this gray layer in Fig 32 looks like it is the same as that in Fig 4. An XEDS spectrum should confirm this - bear in mind the different magnifications in these photos.
I aim to make conclusions after the red and gray layer analysis with regard to the samples, however, it is clear that the sample in Fig 31 does not share the characteristics of the others and therefore it must be concluded that it cannot form part of the data set.
So what is it and why hasn't further examination been carried out before continuing analysis with the other samples? We clearly have two different samples so which one is thermite? An anomaly such as this should be examined as a first priority because it questions the method used for extraction of the samples in the first place.
XEDS analysis of the gray layer in "chip - Fig 31" will also throw up anomalies and further questions.