Holloway Quarry

Holloway Quarry is located in Newport, an unincorporated community within Berlin Charter Township, Monroe County, Michigan, USA. Michigan is part of the Great Lakes region, and Monroe County is in the southeastern corner of the state, adjacent to Lake Erie. This positioning places the quarry in a region with significant geological and ecological importance, near the city of Monroe (the county seat) and other towns like Rockwood and Maybee, which also host mineralogical sites.

The quarry is renowned for its mineral diversity, particularly appealing to collectors. It produces:

• Celestine: Notable for large, tabular blue crystals up to 20 cm, highly sought after for their aesthetic appeal.
• Calcite: Commonly found as white or colorless crystals, often associated with celestine.
• Strontianite: A less common strontium carbonate, adding to the quarry’s uniqueness.
• Fluorite: Known for vibrant colors, enhancing the quarry’s appeal.
• Quartz: Present, though less prominent than celestine.

These minerals reflect the quarry’s geological setting, with celestine being a standout for its rarity and beauty.

Research suggests Holloway Quarry is likely situated within the Detroit River Group (Middle Devonian) or Salina Group (Late Silurian), both consisting of dolomite with interbedded shale, anhydrite, and gypsum. These formations are part of the Michigan Basin, a large sedimentary structure formed during the Paleozoic Era when shallow seas covered the region, depositing carbonate rocks and evaporites. The presence of celestine and other evaporite-associated minerals supports this, indicating a host rock rich in such deposits.

While detailed historical records are sparse, Holloway Quarry is also known as Rockwood Quarry and is a separate operation from the adjacent Newport Quarry (Thompson-McCully Quarry). It seems likely that the quarry has been active for several decades, given its listing on mineralogy databases and its role in Michigan’s limestone and dolomite industry, though exact start dates and ownership details are not widely available online.

Berlin Charter Township, where the quarry is located, offers a blend of rural charm and historical significance. It includes two National Register of Historic Places listings: the Detroit River Light (a historic lighthouse) and the Jefferson Avenue–Huron River Bridge (a historic bridge), reflecting the area’s navigational history. The Pointe Mouillee State Game Area, a critical wetland habitat along Lake Erie, is also within the township, known for wildlife and recreational activities like birdwatching. The area’s proximity to Lake Erie adds to its appeal for outdoor enthusiasts.

The evidence leans toward Monroe County having a humid continental climate, typical of the Great Lakes region, with cold, snowy winters and warm, humid summers. Temperatures typically range from 19°F in January to 83°F in July, with an average annual snowfall of 28.5 inches, relatively low for Michigan. Ecologically, the area includes wetlands like Pointe Mouillee State Game Area, important for migratory birds and wildlife, influenced by Lake Erie. While the current climate doesn’t directly form the minerals, it affects collector accessibility, with summers being more favorable for visits.