|Distribution:||Southeastern Minnesota, northeastern Iowa, southwestern Wisconsin, far northern Illinois|
|Geologic Context:||Upper Ordovician, Galena Formation|
|Main References:||Gonsior 1992; Stoltman et al. 1984; Withrow 1983:40, 50-54|
|Diagnostic Features:||The presence of small white specks and sometimes very small, unlined vugs. There does not appear to be substantial variation between various samples of Galena Chert. Texture usually chalky, at least in Minnesota samples. Sometimes exhibits faint, blotchy mottling. Fossils rare (excluding the white specks, which may be fossil fragments).|
|Quarry Sites:||Bass, 47GT25 (Stoltman et al. 1984)|
|Gold Chalcedony||See note under brown chalcedony|
|Grand Meadow Chert|
|Other Names:||Cedar Valley Chert
Use of the name "Cedar Valley Chert" is based on the apparent derivation of this material from the Cedar Valley Formation. This chert is quite distinctive, however, and would not be confused with other silicates from the Cedar Valley Formation. Thus it seems appropriate to use a separate name. The name "Grand Meadow Chert" was proposed by Trow (1981), who initially described this material and the prehistoric quarries from which it was extracted. This name has gained wide acceptance, and is given preference here. This material should not be confused with the "Cedar Valley Chert" discussed above.
|Distribution:||Southeastern Minnesota. Several acres of GMC quarries have been identified near the town of Grand Meadow in Mower County. The additional distribution on this material is not well documented.|
|Main References:||Gonsior 1992; Trow 1981:102|
|Diagnostic Features:||Slightly translucent. Color does not vary a great deal; all samples are some shade of light to medium grey. Color usually, but not always, homogenous. May be banded near cortex or subtly mottled throughout cobble; scattered small white specks occasionally seen. Transmitted light has a golden brown cast. Patination olive green or olive brown. Cortex thin, medium brown, may show fossil casts.|
|May Resemble:||Strong resemblance to Hampton Chert from northern Iowa (to which it may be geologically related).|
|Green Recrystallized Chert|
|Other Names:||West Patricia Chert and other varieties of the material are named according to their specific outcrop of origin. At present, little information is available on these materials. They do occasionally occur at archaeological sites in northern Minnesota.|
|Distribution:||Parts of Manitoba|
|Diagnostic Features:||Most commonly looks like green quartz.|
|See Also:||Jasper Taconite, Kakabeka Chert
Jasper Taconite, Gunflint Silica and Kakabeka Chert are related materials. Together they are referred to a "Animikie Silicates." (This group may also include other raw materials which are not as well known.) These materials have two phases: a transparent, chalcedonous matrix; and particles of varying size, shape and concentration dispersed in the matrix. Each of these materials has a distinctive kind of particle inclusion. It is not uncommon to find what appear to be intermediate specimens which exhibit characteristics of more than one of these materials.Romano (1994) has recently proposed the existence of a variety of metamorphically altered type of Gunflint Silica, which he calls Biwabik Silica. Further information on that material is not provided here, pending examination of raw material specimens and consideration of occurrence at archaeological sites.
|Distribution:||Northeastern and east central Minnesota, northwestern Ontario|
|Geologic Context:||Middle Precambrian, various formations|
|Main References:||Romano 1991, 1994|
|Diagnostic Features:||Translucent to almost transparent, bluish grey or grey to colorless. Almost always contains small black specks which look much like pepper grains. It also has a distinctive "icy" texture which is hard to describe but not difficult to recognize when you have seen a number of samples. Slightly rough fracture surface. May contains areas with red inclusions, grading towards Jasper Taconite.|
|Other Names:||Hixton Silicified Sandstone, Silver Hill Quartzite, Silver Mound Quartzite|
|See Also:||Alma Quartzite
Although Hixton Quartzite and Alma Quartzite are similar in some respects, Alma may be distinguished by its larger grain size and poorer cementing of grains (Penman 1981:7).
|Distribution:||The distribution of true Hixton Quartzite is apparently restricted to the Silver Mound site in west central Wisconsin. Related orthoquartzites have been found to occur in scattered locations in other parts of west central Wisconsin and probably also occur in nearby parts of southeastern Minnesota.|
|Geologic Context:||Upper Precambrian|
|Main References:||Behm 1984; Behm and Faulkner 1974; Bozhardt 1993; Brown 1984; Porter 1961|
|Diagnostic Features:||Individual sand grains visible. Translucent. Color variable, most commonly off white to pale yellow, sometimes orange, purple or other colors. Hixton (and related quartzites) distinguished by whitish cementing material between the grains. This is lacking in drift derived quartzites.|
|Quarry Sites:||Silver Mound, 47JA21 (Brown 1984; Behm 1984; Hill 1994)|
|Hudson Bay Lowland Chert|
|Distribution:||Northwestern Ontario through western Quebec, northeastern and possibly east central Minnesota|
|Geologic Context:||Paleozoic? Known only from secondary contexts.|
|Main References:||Julig et al. 1989:297; Romano 1991|
|Diagnostic Features:||Unusually fine grained; often reveals exceptionally fine details of flake morphology. Often waxy texture. Most pieces show a strong reddish brown transmitted light, regardless of apparent color of specimen (although the color under normal lighting varies a great deal). Homogenous to subtly banded or mottled. Cortex thin, smooth, may resemble a heavy patination. Appears to be dense and very fine grained, and shows very detailed fracture features (flake scars, ripples, etc.).|
|See Also:||Cedar Valley Chert, Sioux Conglomerate Jasper, Jasper Taconite|
|Distribution:||Small pieces of jasper appear to be widespread, although uncommon, in glacial drift in many parts of the state.|
|Diagnostic Features:||Fine grain and homogeneous texture, sometimes waxy. Yellow, olive, brown or red color, presumably caused by the presence of iron. Opaque to slightly translucent. Color solid to mottled.|
|Other Names:||Jaspilite or Jaspillite or Jaspolite, Oolitic Jasper, Jaspery Taconite, Taconite Jasper
Sometimes this material may be called "Taconite", although this term refers to another material.
|See Also:||Jasper; Gunflint Silica, Kakabeka Chert
Jasper Taconite, Gunflint Silica and Kakabeka Chert are related materials. Together they are referred to a "Animikie Silicates." (This group may also include other raw materials which are not as well known.) These materials have two phases: a transparent, chalcedonous matrix; and particles of varying size, shape and concentration dispersed in the matrix. Each of these materials has a distinctive kind of particle inclusion. It is not uncommon to find intermediate specimens which exhibit characteristics of more than one of these materials.
|Distribution:||Chiefly northeastern and east central Minnesota and parts of northwestern Ontario. Small pieces occur across wide areas of Minnesota, but are not common.|
|Geologic Context:||Middle Precambrian, various formations|
|Main References:||Julig et al. 1989; Romano 1991; Steinbring 1976|
|Diagnostic Features:||Almost always cranberry red; bluish black, dark green occur but are rare. Crowded with small, round "oolites." On a thin edge, the rock matrix between the ooliths is transparent. Usually fine grained, good quality. May grade into sections which look more like Gunflint Silica.|
|Quarries:||Cummins, DcJi-1 (Julig et al. 1989; Steinbring 1976)|
|Jaspilite||See Jasper Taconite
It seems that essentially all references by archaeologists to "Jaspilite" (or "Jaspolite") in fact signify the material better called "Jasper Taconite" (or "Taconite Jasper"). While there is a material properly called Jaspilite (Sims 1972:79), it does not resemble Jasper Taconite and apparently was rarely if ever used to make artifacts (Romano 1991).
|See Also:||Gunflint Silica, Jasper Taconite
Jasper Taconite, Gunflint Silica and Kakabeka Chert are related materials. Together they are referred to a "Animikie Silicates." (This group may also include other raw materials which are not as well known.) They each have two phases: a transparent, chalcedonous matrix; and particle of varying size, shape and concentration dispersed in the matrix. Each of these materials has a distinctive kind of particle inclusion. It is not uncommon to find intermediate specimens which exhibit characteristics of more than one of these materials.
|Distribution:||Northwestern Ontario and northeastern Minnesota|
|Geologic Context:||Middle Precambrian, various formations|
|Main References:||Romano 1991|
|Diagnostic Features:||Distinctly layered (in comparison to GFS and JT), resembling a fine wood grain. May share the same "ripply" or "icy" texture discussed under Gunflint Silica. Color brown to olive grey. Transparent matrix crowded with small acicular (needle shaped) inclusions, although these characteristics are not always obvious from macroscopic examination.|
|Knife Lake Siltstone||See siltstone
The specific term "Knife Lake Siltstone" is taken to imply origin from outcrops in the vicinity or Knife Lake, on the Minnesota-Ontario border. Primary deposits of siltstone are much more widely spread than this, however, and secondary deposits are even more widely spread. Therefore it is recommended that the less specific term "siltstone" be used instead in most cases, because it does not imply a specific geographic origin.
|Knife River Chalcedony||See Knife River Flint|
|Knife River Flint|
|Other Names:||Knife River Chalcedony, brown chalcedony
This material is not a chalcedony; it is one of the few materials in the region for which a thin section petrographic analysis has been performed. Although in a descriptive sense it does have a chalcedonous appearance, the term is not recommended. The term "Knife River Flint" is preferable, and strongly recommended.
|Distribution:||The primary source area is in west central North Dakota, especially Dunn and Mercer counties. Significant quantities are found in a wider part of this region. KRF has been documented as very rarely occurring in the form of scattered small cobbles and pebbles beyond the primary and secondary source areas, including the southern half of Minnesota and north central Iowa.
Hlady (1965) reported a source of KRF in the Souris gravels in southeastern Manitoba. This material was later determined to be silicified wood (Syms 1977:32).
|Geologic Context:||Apparently Eocene, Golden Valley Formation (KRF has not been encountered in bedrock context)|
|Main References:||Clark 1984; Clayton et al. 1970; Gregg 1987; Loendorf et al. 1984|
|Diagnostic Features:||Distinctive "coffee" color. Slightly cloudy appearance in all but thin flakes. Internal whitish mottled inclusions. Patina, when present, white to bluish white. Fine grain, reveals good flake morphology. Cortex is usually yellowish white, coarse, laminated. Burned KRF is grey and opaque, although the characteristic brown color is usually still apparent in transmitted light.|
|Quarries:||Numerous (see Loendorf et al. 1984)|
|Lake of the Woods Chert||See siltstone
"Lake of the Woods Chert" generally refers to a finer textured, higher quality, dark variety of siltstone. This is presumably more common in the vicinity of Lake of the Woods (Jon Nelson, personal communication 1992).
|Lake of the Woods Rhyolite||See rhyolite
The relationship (and distinction) between the materials called rhyolite, recrystallized rhyolite and Lake of the Woods Rhyolite is not clear at this time.
|Lake Superior Agate|
|Distribution:||Scattered in glacial sediments in northeastern and east central Minnesota. Distribution not well documented. Brad Koldehoff (personal communication, 1991) found Lake Superior Agate in the Mississippi River channel in southern Illinois, apparently fluvially transported from the main source area far to the north.|
|Geologic Context:||Formed as amygdules in older lava flows, probably by precipitation.|
|Main References:||Ojakangas and Matsch 1982:54|
|Diagnostic Features:||Distinct salmon red color, usually with concentric, light colored banding. Rarely the white bands may be missing; the banding may also not be apparent in a particular flake, depending on how the agate has broken. The center of the agate may be filled with a solid mass of transparent, crystalline quartz. Usually translucent. Often fine grained, waxy in texture.|
|Light Brown Chalcedony||See chalcedony, Hudson Bay Lowland Chert and Knife River Flint|
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