48mm x 31mm
Upon cutting this stone it was revealed to be my first sagenitic agate from the St Cyrus area. Fractured and incomplete it may be, but it is also clearly a beauty. Note the finely banded centre below left-middle, which is also the area that the "spray" of sagenitic inclusions radiates from. These aforementioned inclusions are "gloved" at their tips with the grey-blue chalcedony that surrounds them. Visually it always reminds me of a jellyfish, despite not strongly resembling one as such.
This piece was found on an evening in December 2015, in moderately heavy rain whipped around by gusts of cold wind. I attached no particular importance to it, other than to note the clear reddish sagenitic "spot, sunken at its edges and slightly risen at its centre.
I would say that out of every 100 agates cut from this location, perhaps seven might be expected to exhibit sagenitic markings or inclusions. Of those seven, perhaps only two or three might be exceptional enough in appearance to warrant polishing. That said, if I were talking about Usan, which is the other location I have spent the most time exploring, I might say two or three sagenitic agates might be expected to be found amongst 200 cut stones. However, there is at least one Usan location where sagenitic agates are common, albeit generally unremarkably marked. As a whole, finer examples are to be found at St Cyrus, although colour is more likely to occur in agates from the former location.
Often sagenitic agates exhibit "spots" that are not eyes, generally also not being associated with patterning in chalcedony but clearly more associated with the "skin" of the nodule, and more often rosy in colouration and as I have said both slightly raised and sunken. These are the epicentres from which the sprays of needle-like zeolitic crystal radiate. Of course, some sagenitic nodules exhibit NO "spots" whatsoever. Telling which nodules may be sagentic becomes more of an artform at this stage. Oddly arranged areas of colour may indicate sagenite, or celadonite inclusions mainly centred around the stone's base. Also, in some rare occurrences weathering may reveal the persuasion of the sagenitic patterning within. Of course, in agates found on beaches, a break along an edge could leave no question. Good luck, I hope you find one.