Rockhound Education Page
The purpose of this page it to provide Minnesota Mineral Club members with various interesting mineral science resources.
BIll Nye Rock Cycle
Periodic Table & Minerals
“Dmitry Mendeleev first proposed the Periodic Table of the Elements to the world back in 1869. But fewer people know that he was also a mineral collector. And fortunately his collection is still intact and on display in St. Petersburg University in Russia.” Mindat
Periodic Table Song
Use the mineral’s properties to determine its identity along with comparison to like mineral found in the same area. Many web sites will walk you through mineral identification methods – these usually involve systemic property analysis vs. a chart. Several field books are available for reference while in the field. Note that the properties are determined by the chemical composition and crystal structure, or the way that the atoms are arranged. Mindat is great for mineral identification help with its large locality reference material.
Mineral Identification Strategy
Rock Talk with William Cordua
Our club member Prof. Bill Cordua has generated many great Rock Talks that are specific to the geology of our collecting region!
Glaciers in Your Backyard
Meteorites and Wrongs
Ancient Oceans on Top of Our Hills
The Rock Elm Meteorite Crater
Watch for Fallen Rock
Fluorescence in minerals occurs when a specimen is illuminated with specific wavelengths of light. Ultraviolet (UV) light, x-rays, and cathode rays are the typical types of light that trigger fluorescence. These types of light have the ability to excite susceptible electrons within the atomic structure of the mineral. These excited electrons temporarily jump up to a higher orbital within the mineral’s atomic structure. When those electrons fall back down to their original orbital, a small amount of energy is released in the form of light. This release of light is known as fluorescence. [Basic Concepts in Fluorescence: Michael W. Davidson and others, Optical Microscopy Primer, Florida State University]
How Fluorescence Works
Lake Superior Agate Formation
The exact formation methodology of Lake Superior agates is disputed by content experts. The general geology transition to create Lakers, as described by Wiki below, is agreed upon. Several book authors disagree on if the silicate rich minerals were slowly deposited into gas voids already in the lava, or if the silicate minerals already within the “glob” preferentially nucleated on the inners surface while coming out of solution during cooling. The same arguments go for Oregon Thunder Eggs formation, which are similar in nature. Comments/opinions welcome.
“More than a billion years ago, the North American continent began to split apart along plate boundaries. Magma upwelled into iron-rich lava flows throughout the Midcontinent Rift System, including what is now the Minnesota Iron Range region. These flows are now exposed along the north and south shores of Lake Superior. The tectonic forces that attempted to pull the continent apart, and which left behind the lava flows, also created the Superior trough, a depressed region that became the basin of Lake Superior.
The lava flows formed the conditions for creation of Lake Superior agates. As the lava solidified, water vapor and carbon dioxide trapped within the solidified flows formed a vesicular texture (literally millions of small bubbles). Later, groundwater transported ferric iron, silica, and other dissolved minerals passed through the trapped gas vesicles. These quartz-rich groundwater solutions deposited concentric bands of fine-grained quartz called chalcedony, or embedded agates.
Over the next billion years, erosion exposed a number of the quartz-filled, banded vesicles—agates—were freed by running water and chemical disintegration of the lavas, since these vesicles were now harder than the lava rocks that contained them. The vast majority, however, remained lodged in the lava flows until the next major geologic event that changed them and Minnesota.
During the ensuing ice ages a lobe of glacial ice, the Superior lobe, moved into Minnesota through the agate-filled Superior trough. The glacier picked up surface agates and transported them south. Its crushing action and cycle of freezing and thawing at its base also freed many agates from within the lava flows and transported them, too. The advancing glacier acted like an enormous rock tumbler, abrading, fracturing, and rough-polishing the agates.” [source: Wiki]
Lake Superior Agate
Lake Superior Agate Hunting Tips
Moose Lake Agate and Geological Interpretive Center
|Thanks to Phil Gotsch, a former Minnesota Mineral Club president, the Moose Lake Agate and Geological Interpretive Center at Moose Lake State Park is a reality. Dedicated in 2004, the center is devoted to Lake Superior Agates and minerals of Minnesota. The club contributed funds toward the showcases in the center and various members lent or donated pieces from their collections. Phil championed the cause across the state and encouraged local clubs to work together to create MAGIC.The Moose Lake 4,500 square foot building, located at the entrance to the park, includes a multi-purpose classroom, nature store gift shop, park offices, a resource workroom, restrooms, and an exhibition hall that showcases Minnesota’s gemstone, the Lake Superior Agate. Interpretive displays focus on rocks, minerals and geology of Minnesota.Hours:
April- Memorial Day office hours: intermittent.Memorial Day through Labor Day office hours Friday-Sunday 10:30-6, Monday 12-2, Tuesday/Wednesday closed, Thursday 12-2. Labor day through October office open intermittently
4252 County Road 137
Moose Lake, MN 55767
Located 1/4 miles east of I-35 at the Moose Lake exit #214. The park entrance is off County Road 137. Take the Moose Lake exit off I-35. Then go east on County Road 137 until you see the park signs about 1/2 mile down the road.
Stromatolites & the Minnesota Iron Range
If you have ever been to the Smithsonian Museum’s mineral section you probably saw a stromatolite from Minnesota. Here is a web page that describes some collecting of this mineral along with many others. It has old info (2000) but still is interesting. Here is an example: “Mary-Ellen Jasper is the fossil of stromatolites, a form of blue-green algae of the late precambrian era. These fossils are 1.8 to 2 billion years old and are believed to be among the earliest forms of life on earth. The stromatolites would produce oxygen in a marine environment that was rich in ferrous (iron in the +2 oxidation state) ions. The combination of the ferrous iron and the oxygen would cause precipitation of the hematite minerals along with the silica (quartz). Mary-Ellen Jasper has a hardness from 6.5 to 7 (the same as glass – quartz) with colors of red, pink, white, yellow and even green. It occurs commonly in the Biwabik Iron Formation forming bands of iron and chert in the Mesabi Iron Range.”