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Source article
|
Techniques
(elements analyzed) |
Age of
chert |
Location
|
Chert color range
|
Summary of results
|
|---|---|---|---|---|---|
|
Leudtke (1978) |
INAA (Sm, Yb, Lu, La, Np/U, Sc, Na, Br, Ce, Th/P, Cr, Hf, Ba, Cs, Co, Rb, Eu, Sb, and Fe) |
early Mississippian |
Oceana County, Michigan |
Gray to brown |
1. Gray chalcedony had smaller proportions of all analyzed elements, except uranium and bromine. |
| 2. Sandy brown chert had the greatest proportions of all elements, except uranium and bromine. | |||||
| 3. Gray chert is intermediate for all elements. | |||||
| 4. Chemical variations can exist within formations. | |||||
|
|
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|
Frasier et al. (1972) |
Flame AAS (Na2O and K2O) |
late Cambrian to Mississippian |
Illinois: Union County, Johnson County, Alexander County, Hardin County, McDonough County, Brown County, Kankakee County, Adams County |
Black to gray to brown |
1. Chemical composition varied mainly in the relative amounts of SiO2 and CaO.
|
| XRF (TiO2, Al2O3, Fe2O3, MnO, MgO) | Nevada: Hardin County | ||||
| California: San Francisco (Twin Peaks) | |||||
| Montana: Granite County, Near Old Mines | |||||
| Ohio: Flint Ridge Park | |||||
| Indiana: near Veedersburg | |||||
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|
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|
Hein et al. (1975) |
X-ray mineralogy (quartz, calcite, smectite, hematite, illite, feldspar, barite, anhydrite, chlorite, apatite, gypsum) |
early Cretaceous to early Pliocene |
Deep Sea Drilling Project Leg 62: Central North Pacific Ocean, Mid-Pacific Mountains, Hess Rise |
Orange to brown to gray to black |
1. The carbonate component of the chert is distinguished by high values of MgO, CaO, Mn, Ba, Sr, and Zr. |
|
XRF (Mn, Ba, B, Zn, Ni, Y, Zn, Cu, Mo, Cr, Cu, SiO2, CaO, Al2O3, Fe2O3, CaO, Na2O, K2O, MgO) |
2. Tuffaceous cherts have high values of K and Al, and commonly Zn, Mo, and Cr. | ||||
| 3. Pure cherts are characterized by high SiO2 and B. | |||||
| 4. High B percentages may be a good indication that the chert formed in an open-marine environment, isolated from terrigenous materials. | |||||
Notes: INAA = instrumental neutron activation analysis, AAS = atomic absorption spectroscopy, XRF = X-ray fluorescence.