The in-house standard ES-2 ("Dictyonema Shale
") was used as reference material .
In-house standard ES-2 ('Dictyonema Shale
') was used as a reference sample (Kiipli et al.
(86) During the implementation of the Soviet uranium project, a top secret uranium factory (Kombinat No 7) was erected in Sillamae, and a test facility, officially called paint factory (krassilnaja fabrika), was established in Narva to test and develop the technology of extracting uranium from the Dictyonema shale
found in north-eastern Estonia (the average uranium content of Dictyonema shale
is 0.028 per cent).
The target was composed of the stratified sedimentary cover comprising (from the top) bedded Upper and Middle Ordovician limestone (up to 20 m thick), Lower Ordovician Dictyonema shale
(argillite with an admixture of organic matter, about 2 m thick), and an up to 200 m thick layer of Lower Ordovician to uppermost Vendian sand, silt, and some clay, which covered the Precambrian basement consisting of granites, gneisses, amphibolites, and other crystalline rocks.
However, there is another type of oil shale in Estonia known as graptolite argillite (the older term Dictyonema shale
In the world OS overviews, the Estonian kukersite and Dictyonema shale
reserves are assessed on the basis of their energetic value.
The name was applied to a transition between the Dictyonema Shale
(with many interbeds of quartzose sandstone in the lower part) of the Turisalu Formation and the Obolus Sandstone represented in NE Estonia.
The occurrence of Middle Cambrian to Late Ordovician organic-rich black shale deposits in an extensive area of Sweden (alum shale ), the Oslo region , Bornholm , Estonia (known as graptolite argillite, "Dictyonema shale
" , and kukersite as proper oil shale), Poland  and NorthWest Russia  has been known for a long time.
Pyrite varieties in Estonian Tremadocian argillite (Dictyonema shale
One sample comes from the Tremadocian graptolite-argillite, the Dictyonema shale
or argillite, as it was called in the earlier literature (for the change of the name see ), from a shallow shelf setting.
For this aim, model mixtures consisting of kukersite flotation concentrate ([A.sup.d] - 9.3%, [CO.sub.2.sup.d] 0.2%), and its main minerals [alumosilicates, carbonates, pyrite, quartz, kaolinite and halloysite, and enrichment residue of Dictyonema shale
However, on Bornholm at the borderline between Baltica and Avalonia, the orogenic heating of the local black Dictyonema shale
reached CAI value of 3.5 or 190 to 200[degrees]C .