For the explanation of the conditions of pressure and of temperature at the emergence of agates are agates, whose formation clearly within the diagenetic range (standard temperature and - pressure ratios) took place. A good example for this is this amber from Golling, which belongs to the collections of the amber cabinet of the museum at theLoewentor in Stuttgart.
… So far one knew pieces of amber of this deposit with quartz-filled veins (…), but this piece donated by Mr. Dr.R. Kalwait is surprising because of its large agete-nodule and beautifully colored Chalcedony. The agate shows the typical parallel banding with the usual agate peculiarity that the bandings form pronounced angles in the corners (instead of roundnesses). A black zone of curved lines probably represents the carbonaceous remainder of compressed wood layers. The amber has its original form and colouring changed during its storage in the rock (...). The whole quartz material of the agate-nodule and the chalcedony-inclusions is standing over quartz-filled veins in connection with the surface of the specimen, so that the way of the quartz solutions into the cavities is clear. In addition, the amber surface is covered with this piece not with a quartz crust….
Source: Dieter Schlee, the amber cabinet, handbook to the amber exhibition in the museum at the lion gate Stuttgart, Stuttgart contributions to the natural history, ISSN 0341-0161
Unfortunately I had to state within a visit of the cabinet that this specimen was worked on only insufficiently. The piece was formed and polished with the conventional materials of the treatment of amber , which is sufficient for the amber matrix. But the full beauty of the agatecould not be prepared in this matter. The agate inclusions are dull and are showing still the scratches from the sawblade.
A further similar piece with the discovery site Kuji, Japan belongs likewise to the Collection of the amber cabinet.
This is the link to the website of the Loewentor museum in Stuttgart.