Provenite

Middleville (Herkimer diamond district)

AreaActiveDraft data

43.1383° N, 74.9694° W · ± 10 km

Pyrite, Quartz and Rock crystal from New York, United States, with photos of specimens from this locality.

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Minerals found here

PyriteQuartzRock crystal

On the same specimen

Same specimen Pyrite included in Quartz

Herkimer-type quartz crystals commonly contain small inclusions of minerals, including pyrite, alongside calcite, dolomite and sphalerite.

Inclusions inside the clear, doubly terminated crystals add interest and are prized in Herkimer quartz.

Sources: SRC-139

Pyrite at Middleville (Herkimer diamond district)

Formula
FeS₂

Sources: SRC-139

About Pyrite →

Quartz at Middleville (Herkimer diamond district)

Formula
SiO₂

Sources: SRC-139

About Quartz →

Rock crystal at Middleville (Herkimer diamond district)

Doubly terminated, very clear crystals grown free inside dolostone vugs, often with black hydrocarbon inclusions.

Formula
SiO₂
Morphology
Doubly terminated crystals (pointed at both ends), as singles, doubles and clusters
Typical size
From a couple of millimetres to over 20 cm; cavities range from pea-sized to several feet across
Color / luster
Colourless to smoky, transparent; solid hydrocarbon inclusions can cause the smoky tint
Associated minerals
Dolomitecalcitepyritesphaleritedrusy quartzblack tarry hydrocarbon
Availability
Commonly available
History
The crystals were known to the Mohawk people and early settlers, who used them as amulets and tools and traded them to other groups.

Sources: SRC-139

About Rock crystal →

Geology of the locality

Setting
Quartz grew in solution cavities (vugs) of the silicified Cambrian Little Falls Dolostone, deposited in a shallow sea roughly 500 million years ago.
Host rock
Little Falls Dolostone (Cambrian)
Region
New York
Country
United States

Coordinates are those of Middleville village (Wikipedia), around which the commercial fee-dig mines (such as Ace of Diamonds, Herkimer Diamond Mines and Crystal Grove) lie, so only district-level accuracy is claimed. Collecting on public land in New York is prohibited and private land needs permission.

Sources: SRC-139 SRC-087

Sources

  1. SRC-139 · Website
    Herkimer diamondsKing, H.M. · Geology.com
  2. SRC-087 · Website
    Middleville, New YorkWikipedia

Draft data from the Provenite workbook. Check entries against the cited sources before relying on them. Photos are open-licence images from Wikimedia Commons; the author and licence are given with each photo.