Michigan Stone Info
We pride ourselves on our large and varied selection of Leland Blue, Fordite, Petoskey Stones, Copper Fire Brick, Native Copper, Michigan Green Stone and many other native to Michigan stones and materials. Whether it's a natural stone or an upcycled by-product, Michigan has produced stunning materials for us to work with.
Michigan's State Stone
This interesting stone is a variety of calcite. It was formed by the fossilization of ancient coral, Hexagonaria. The coral lived in shallow waters and today’s fossil often includes ancient silt and mud. Petoskey Stones are often found on many beaches of Lake Michigan and Lake Huron, as well as in rock quarries from Traverse City to Alpena. The honeycomb patterned stone has a hardness from 4 to 5 and is the official state stone of Michigan. This fossil is around 350 million years old.
Fordite, AKA Detroit agate, is an interesting and historic byproduct of a bygone age. These unique “gems” are actually layer upon layer of enamel paint which built up over time in the Ford auto plant paint booths as each car was spray-painted individually. When the paint accumulated into thick layers, it became necessary to remove it, which auto workers did by cracking it off with hammers. The vast majority of this material was discarded, but fortunately a few workers were familiar with lapidary (art of stone-cutting) and salvaged some choice pieces. Today, this relic of our industrial history is very rare, valuable, and prized.
Copper fire brick
1870 to 1940
This unusual lapidary material is actually a historic relic of the copper mining era in the Lake Superior district of Michigan’s Upper Peninsula. The ceramic fire bricks that lined the copper ore smelters gradually eroded over the decades of use. The molten copper in the smelters then filled these voids in the bricks. When this great chapter of mining in Michigan ended in the mid 1950s the smelters were torn down and the bricks were shipped off to be re-processed for the value of the copper. Only small amounts of the old bricks were left behind for stone cutters and jewelers to discover. Copper Fire Brick is truly a unique recycled “gem” of Michigan.
Leland Blue (AKA Antique Foundry Glass)
This unique material was a byproduct of the short-lived days of smelting iron ore in Northwestern Michigan. The Upper Peninsula Mesabi iron ranges supplied the ore. A high grade charcoal made only from beech and maple combined with local limestone flux reduced the iron ore to pig iron, creating a unique foundry glass. Smelting began in 1875 and by 1900 had ceased due to lack of hardwood. The byproduct was dumped into Lake Michigan and shows up from time to time on the beaches from Leland to Traverse City.
This gemstone was made our Michigan State gem in 1972. It is unique to Isle Royale and a few old copper mines on the Keweenaw Peninsula. The name translates to “Green Star Stone.” It is a gem form of the mineral pumpellyite that filled the tiny gas pockets (vesicles) of the billion year old basalt flows that underlie the Keweenaw and Lake Superior.
Mohawkite is one of the rarest and most interesting of all the gem materials found in Michigan. It was discovered in only two copper mines in the Keweenaw Peninsula, the Mohawk and the Ahmeek. It is a combination of copper, nickel and silver in white quartz. The distinctive “snowflake” pattern Mohawkite is highly prized by jewelers and gem collectors. None of this material has been mined for over 70 years.
Mineshaft basalt is a highly attractive and rare copper ore from the Wolverine Mine in the Keweenaw Peninsula of Michigan's Upper Peninsula. This material when the county road commission was crushing the mines rock pile for gravel. Our lapidary, Gary Wilson, went to the sire and saved as much as he could. It is and igneous material dating back a billion years or more! The stone contains pockets filled with a variety of minerals including epidote and feldspar crystals, and of course copper. Mineshaft basalt cannot be found anywhere else in the world.
Lake Superior Agate
World renowned for their stunning, translucent beauty, Lake Superior Agates are a variety of the mineral quartz. The combination of quartz with small amounts of different elements has created beautiful banding, varied patterns, and eye catching colors unique to each agate. These 1.1 billion year old gemstones can be found in and around Michigan's Lake Superior.
Once again, Gary B. Wilson’s innovative lapidary skills have brought us a stunning new material. Exclusive to On The Rocks, Michigan Mosaic is a unique combination of Fordite, Leland Blue and Petoskey Stone infused with copper. This limited material boasts the best Northern Michigan has to offer.