Nature Watch: Mineral discovery raises questions


Q: We have two questions: Donald found a rock in the driveway that looks to his father (Mark) to be a common one. Inside, after we cracked it open with a hammer, we found it to be mostly light gray in color with sparkly bits of glitter (schist?). Some of it is pure white.

Donald could scribble with it on what's left of the blacktop on our driveway, so initially he thought it was chalk. Mark's guess was marble. What do you guess?

Is there a rocks and minerals club in Pittsfield, possibly at the Berkshire Museum? If so, how would someone go about signing up?


A: Without seeing it and from the information you offer, I can only guess.

You may be correct in assuming it marble. The Housatonic Valley is built upon a bedrock of marble, a metamorphic rock, that, in places, is of high quality.

It is primarily calcium, making it much softer than glass, or the mineral quartz or its rock form quartzite.

I cannot see marble leaving a mark on asphalt (which is much softer) though. If the sample you have can be scratched with a screwdriver, I'd say marble; otherwise quartzite.

If it is marble of local origin, it is most likely Stockbridge marble, found in various colors, but mostly white, light gray and sometimes layered with schist and even quartzite, among other rocks mixed in.

Many of our surface rocks, pebbles and gravel baffle me because I know they were left by the glaciers (or as fill by road crews) and came from other places.

Even so, as a young mineral collector, I would find an array of specimens to add to my equally young collection -- pebbles of such minerals as brick-red jasper, jet black jasper, clear, milky and smoky quartz, rust-colored limonite. All but the limonite was found on the gravel road leading to Wahconah Falls.

I recall walking a gravel road in Chester, Conn., many, many years ago and finding garnet crystals the same diameter as nickels and quarters. Long gone, I expect.

I so much wish that there was still enough interest among young people to sustain a rock and mineral club at the Berkshire Museum. Perhaps there is and I am out of the loop. There is a mineral (and gem) club in North Adams. The Northern Berkshire Mineral Club meets from 6 to 8 p.m. on the third Thursday of the month from October through April at the North Adams Public Library, according to the club's web site (

The contact person listed is Larry Michon, and his email is:

Mailing address is PO Box 297, North Adams, MA 01247

The Greylock Mineral Club, the organization I joined when I was about 10 or 11 years old, is listed on the Internet as meeting at a Pittsfield church. But when I phoned the church to confirm, the person I spoke with had no knowledge of them meeting there.

A listing of statewide mineral clubs that will be of interest to young people is at

If readers know of any other mineral clubs, in our area (nearby counties in New York, northwestern Connecticut, or Western Massachusets let me know.

Questions and comments for Thom Smith: Email


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