Penfield Quarry

For one Saturday morning in May, The Dolomite Group opens its Penfield Quarry (746 Whalen Rd.) to collectors.  This year that Saturday was May 6th. They asked that folks arrive before 7:00 AM to sign in, receive an official welcome, and attend a brief safety meeting.  Immediately after, everyone descended to a level in the quarry that has been set aside for collecting (see photo on page 1).  Hard hats (or bicycle helmets for kids) are required as is eye protection.  No open toed shoes/sandals are allowed.  The collecting period was from 7 AM until noon.

Penfield Quarry was established in 1920 as a rock aggregate quarry in the Silurian Lockport Dolostone.  The quarry operators supply more than 20 different styles and sizes of crushed dolostone product for use in construction, road fill, landscape, etc.  Penfield is only one of the regional quarries operated by The Dolomite Group.  Walworth Quarry, which holds a similar Open House in October, is another.

Penfield Quarry in 1928.
Photo from The Dolomite Group webpage

The dolostone rock is hard, no, it is very hard!  Rock hammers and chisels are a must to break rock.  Larger sledges are even better.  Conventional hammers are not designed for this sort of work and are unsafe as they can break rather than the rock.  Of course, there are smaller rocks around and you might be lucky just searching in the parking area or along the edge of the larger pieces.

The prize is a large colorful, perhaps transparent, cubic fluorite sitting in a vug and perhaps accompanied by bright white rhombohedral dolomite crystals (see previous note on western NY dolomite).  But the vugs can also contain dogtooth calcite, selenite (crystalline gypsum), sphalerite, and even, occasionally galena.   Chain coral (halysites) and other fossils can be found in the dolostone.

Penfield Fluorite: WCGMC member Bob Hiler grew up on a fruit farm in Penfield and has been collecting at the quarry for much of his life. In fact, his collection of western New York fluorites was featured in the “Mineral Collections in the American Northeast”, a wonderful 450 page supplement volume to the Mineralogical Record July-August 2016 issue. Bob’s fluorite depicted here is 3.8 cm on side, resting comfortably on a bed of white dolomite.
Photo by Jeff Scovil (Min. Rec., 2016)

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