Lake Michigan borders the western edge of Michigan while Lake Huron borders the eastern periphery. A part of Michigan lies to the north of the main land mass and south of Lake Superior. Michigan has a large variety of minerals spread all over the state.
Lake Superior Agate
Agate is a type of quartz which is generally found in banded form. Agates are found mostly in volcanic rocks and are also associated with metamorphic rocks. Lake Superior agates are very famous and are distinctive by its richly colored bands due to oxidation of the iron present in the mineral.
The Lake Superior Agates are characterized by its orange, yellow and red colors. The bands can also be in black, grey dark brown or white colors. In Michigan, the Lake Superior agates can be found along the shores of Lake Superior and many sites where the mineral can be found. Searching along the shores of the lake will still produce some nice specimens. They are beautiful as you find them, but slabbing and polishing them will often bring out the brilliance of their banding.
Copper Nuggets and Crystals
The Copper Country area which is situated in the western side of the Upper Peninsula of Michigan has large deposits of copper. The copper found in this area is unlike other copper deposits as the copper is not in the form of copper sulfide or copper oxide but as pure copper. This is vastly different from most copper deposits throughout the world, where tiny bits of copper must be extracted from ores.
Huge masses of natural copper sometimes weighing a few hundred pounds and even thousands of pounds have been found in the mines in the Keweenaw Peninsula in Houghton County.
Copper crystals in clusters have also been found in this area which has had extremely productive copper mines for over a hundred years. Some of these crystals are exceptionally beautiful and interesting, and are highly valued by mineral collectors.
Copper has also been mined from quarries in Keweenaw County and Ontonagon County in the state. Central Mine located in Keweenaw County and the Caledonia Mine in Ontonagon County are two places which offer pay and dig facilities for amateur mineral collectors.
Amongst the active mines in Michigan is the Eagle Mine Project which is situated in the Yellow Dog Plains in Marquette County and the Copperwood Mine in Gogebic County.
Float copper can be found by metal detecting in these known copper-bearing regions of Michigan Upper Peninsula.
Chlorastrolite is also known as greenstone or the Isle Royale greenstone. The gemstone was officially designated as the state gemstone in 1973.
Chlorastrolite is a variation of the mineral called pumpellyite. Michigan is the only state where gem quality greenstone has been found. The best quality gemstone has been obtained from the Isle Royale Mines in Lake Superior in Keweenaw County. Chlorastrolite has also been found in Delaware Mines located in Keweenaw County.
Other places where the mineral can be found are Calumet and Hecla mines, Centennial Mine, LaSelle mine, Quincy and Hancock mines which are located in Houghton County. Some other places in Keweenaw County where chlorastrolite has been found are Copper Harbor, Clark mine, Central Mine, Medora Mine, Copper Falls mine and South of Eagle Harbor.
Select pieces of chlorastrolite can look very beautiful when cut and polished into cabochons.
Petoskey Stone has been the designated the state rock of Michigan State. Petoskey stone is actually a fossilized coral. It is named after the town of the same name as a number of these coral stones are found in the area.
The Petoskey stones appear as pebbles and are quite commonly found in the northern side of the Lower Peninsula. When dry, the stone looks like the ordinary limestone but in wet condition or when it is polished it resembles a coral fossil.
The stones are parts of coral reefs belonging to the Devonian Period almost 400 million years ago. It is found in various beaches and even in some inland locations. The Gravel Point Formation of the Devonian period located in Michigan is a source for Petoskey stones.