bb: Baryte - Bright FL Striped Crystals from Linwood Mine, Iowa

Description

NOTE:
Postal delays caused by the pandemic are affecting
delivery of parcels. In the USA, most delays are minimal. Shipping to other countries is currently taking at least several days to a week or more longer than usual. Please keep this in mind while bidding.
Species:
Baryte
Locality:
Skunk Pocket, Linwood Mine, Buffalo, Scott County, Iowa
Size:
Cabinet - 6.2 x 5.0 x 1.5 cm
Weight:
51.2 g
Number:
2489
Details:
Here's a sharp cabinet specimen with crystal surfaces preferentially covered by a late stage of tiny baryte crystals that sparkle like sugar on gumdrops. UV collectors prize this baryte for its zoned fluorescence: bright snow-to-blue-white under all UV wavelengths, with long-lasting yellow to greenish phosphorescence. This interesting material comes from a very unusual underground rock mine in Iowa, which started as a surface quarry around 1897 before switching to subterranean extraction in 1956. It was not well known for mineral specimens until about 2005, when it started producing lovely clear calcite crystals with marcasite inclusions. A few years later, operations broke into large pockets of huge, olive-brown baryte crystals that caused a sensation. Both minerals are still coming out, although in more modest sizes; the baryte seems to change from pocket to pocket, so the individual pockets are being given descriptive names a la the Sweet Home Mine.
NOTE: TO VIEW FLUORESCENCE, YOU NEED A QUALITY ULTRAVIOLET LIGHT WITH A UV FILTER!
The better the UV source, the better fluorescent minerals look. Cheap "UV" flashlights without filters will not provide satisfactory results!
The photos here are taken using Convoy S2 and C8 (longwave-365)
and UV Systems SuperBright II (shortwave-254) lamps, metered
and exposed to show fluorescent response to best advantage.
Key factors include lamp wattage, UV spectrum and filtration, as well as distance from lamp to specimen. For best results with any UV source, observe against a dark, non-fluorescent, non-reflective background, in complete darkness with eyes adapted. For extended viewing, use protective UV-absorbing goggles.
° ° ° ° °  PLEASE READ BEFORE BIDDING  ° ° ° ° °
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INTERNATIONAL CUSTOMERS:
* US Post Office policy can make economical shipping a challenge. Price increments for packages are as follows:
First class up to 225 g, then 225-900 g, then 900-1350 g (Canada only).
Higher weights require Priority Mail.
I always try to make shipping as cost-effective as possible. Please send a message so we can work things out.
* Please note that import duties, taxes or charges are not included in the item price or shipping fees and are the
buyer’s
responsibility.
While most countries do not charge duty on mineral specimens, you should check in
your own co
untry to be sure before bidding.