SouthDakota

South Dakota fluorescent minerals

The first two rows are fossil sponges from the Bad Lands of South Dakota. The age is from the Oligocene or about 28 to 37,5 million years old. The photos in the left hand column show the specimens in natural light to be a white to tan to grey color. In the center photographs, for the first two rows, the color is the result of reflection of the long wave ultraviolet light off the otherwise white or light colored surface and not fluorescence. The short wave light photo to the far right brings out the full color of the specimen. Since the sponge was replaced by chalcedony we had hoped it would fluoresce green and it does. In the second row short wave photo there is a little bit of pink to the upper middle on the left side and to the lower middle on the right side. This is calcite. The purple again is just the reflection of the light off the otherwise light colored surface.

The second two rows are chalcedony from South Dakota. The images to the left are shades white to tan, brown and grey in normal light. The images in the middle show a blue to purple reflection from the long wave light with just a little green fluorescence in the top image. The third photo is taken with a short wave light which gives a nice bright green. The purple is a reflection from the light and not fluorescence. In the bottom photo you will notice a pink fluorescence in the center of the specimen. This is calcite.

The next three rows are Baculites from South Dakota. The species are most likely Baculites cuneatus or compressus and are from the Upper Campanian Stage of the Upper Cretaceous, (they are approximately 72-73 million years old). The specimens in the left hand column are shown in natural lighting. The first two rows show the external surface with suture lines showing. The third row shows the internal crystal lined chambers exposed and septum walls. The replacement material is calcite (white, yellow, and orange) and chalcedony (green). The purple is a reflection of the lights off the otherwise nonfluorescent, light colored, surface of the fossil. The second column shows the specimens under long wave ultraviolet light. The South Dakota specimens seem to fluoresce best under long wave. They fluoresce somewhat less strongly under short wave ultraviolet lights as you will notice in column three. The septum wall break areas do seem to be a little brighter under short wave, but this may be due to the darker nonfluorescing background.

The next two rows are ammonites. The first appears to be a specimen of Menuites portlocki complexus. They occured in the Middle Campanian Stage of the Upper Cretaceous (about 77-78 million years ago). The first, left most image is under normal light, The middle image was taken under long wave ultraviolet light and is the stronger fluorescing image of the two. The right most image was taken under short wave ultraviolet light. The next row of images are of a Rhaeboceras from the Upper Campanian Stage of the Upper Cretaceous (about 71-72 million years old). As with the ammonite above it the middle image, under long wave ultraviolet light, is the stronger fluorescing of the two. The internal structure is nice to be able to view. Especially when it fluoresces.

The next specimen is a Placenticeras meeki. They occur in the Upper Campian of the Upper Cretaceous (about 74-72 million years ago). As with other South Dakota fossils the calcite in the specimen fluoresces yellow and the chalcedony fluoresces green. The stronger fluorescing image is under long wave UV light.

The next row has a nice sized Hoploscaphite (top) and a Jeletzkytes (in the shadow to the right). They ranged from the Middle Campanian Stage to the Lower Maastrichtian Stage of the Upper Cretaceous (80-69 million years ago). Neither specimen fluoresces. There is an orange calcite glow (lower middle) of the long wave photo. The interesting thing about this specimen is the blue-white fluorescence under both the long and short wave ultraviolet lights I am uncertain of the mineral.

The long ribbed fossil with two rows of bumps is a section of Didymoceras which lived during the Middle Campanian Stage of the Upper Cretaceous (about 77-78 million years ago). The fluorescent minerals here appear to be calcite and chalcedony with the brighter fluorescence occuring under long wave.

The last row off fossils is a bivalve. The calcite glows a light yellow-white under both long and short wave. The stronger fluorescence is under long wave. The is also some orange fluorescing calcite at the bottom middle of the specimen in the photo.

Regular lighting

Long wave ultraviolet light

Short wave ultraviolet light