Snake Hill, New Jersey Revisited

Mineral Matters #759

A little while back, I wrote about a stilbite specimen from Snake Hill, New Jersey. This was in Mineral Matters #741.

In it, I mentioned that the stilbite sat on white calcite that fluoresces pink under longwave UV (LW). I was asked if I had, or could take, a photo of the fluorescent response (which I now done).

I have a few other specimens from the location, so I thought I should check each for a fluorescent response. There are a few that fluoresce.

The interesting thing, to me anyway, is that the same mineral species from the same locality, can react in different ways.

For example, the (white) calcite on the stilbite specimen only fluoresces pink under longwave. I then found the following responses on other specimens:

Colourless/white calcite: Fluoresces red. It fluoresces strongest under shortwave (SW), then midwave or medium wave (MW), then weakest under LW. The SW response is quite intense!

Orange brown calcite with pyrite: Fluoresces bluish white with a green afterglow (that fades quite rapidly when you remove the UV source). It fluoresces strongest under LW, then SW, then weakest under MW.

Datolite with minor white calcite: The datolite crystals are green. Under SW, there is a small amount of calcite evident that fluoresces red. No response under other wavelengths.

This variety just goes to show that you should check specimens under each wavelength!

Below: 5835 Datolite and calcite, Laurel Hill (Snake Hill; Penitentiary Quarry), Secaucus, Hudson Co., New Jersey, USA. Width of view 14mm. SW UV response.

Below: The same specimen under white light.