This is an Great Block of a Green River Insect block. This is a March Fly and beetle along with several other insects trapped in the layers of rock well known from a classic site in Colorado. The preservation and detail is exquisite.
It is Eocene in age, 50 Million years old from the Green River Formation in Colorado.
This formation is known for the insect fossils and leaves coming from that area. The fossilization is exceptional for these small invertebrates.
This one comes complete in this Glass Topped leatherette collectors case 6 x 8 inches.
The photograph in the frame is an enlargement of the actual insect inside the case.
This is the specimen you will receive.