From mid-2021, newsletter articles are no longer posted separately here. Interested readers should scan through the newsletter headings under the ‘Newsletters’ tab.

FACETIPS – A GEM CUTTER’S NOTEBOOK

by
Duncan Miller


The faceting articles published over the past few years in the Mineral Chatter have been compiled into a single 128 page document, available for download for those interested in saving all the articles together. To download the pdf file click here.

A 29,18 ct cuprite from Onganja, Namibia, cut by Duncan Miller and now in a private collection in Germany.


Browsing Archive: April, 2021

Hidden Treasures

Posted by Site Moderator Webmaster on Tuesday, April 27, 2021, In : Mineralogy 

Jo Wicht

Who would have thought that some of the most boring looking mineral specimens could be the most spectacular under shortwave fluorescent light? Look at these three, for example…

 

 

 

Over time I have made a point of collecting specimens if I am aware that they fluoresce because that is fun, but often one acquires others unknowingly. Because I agreed to take some photos to supplement this edition of the MinChat, I shone my UV light over my entire mineral collection to see what I coul...


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DISTINGUISHING RUBY FROM GARNET AND RED GLASS USING FLUORESCENCE

Posted by Site Moderator Webmaster on Monday, April 26, 2021, In : Mineralogy 

Duncan Miller

Cut rubies, red garnets and red glass can look very similar. There are several techniques that can be used to determine if a red stone is a ruby. These include a semi-destructive relative hardness test (ruby will scratch garnet and glass, but not the other way around); using a polariscope to test for birefringence (ruby is birefringent whereas glass and most garnet are not); and using a dichroscope to see the two pleochroic shades of red in ruby (which are absent in garnet and ...


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Feldspar, or so I thought….

Posted by Site Moderator Webmaster on Monday, April 26, 2021, In : Mineralogy 

Willie Lombard

I collect different species of minerals and rocks of SA and Namibia and need only one good example of each. Right across from the old Swanson Enterprises building in Springbok is an open yard with some large heaps of rocks and minerals. I asked the resident on the property if I could have a look-around. No problem. Found some fluorites and a good example of a diorite. There were some feldspars and a lot of pegmatites. I was sleeping over, so I asked the resident if I could ret...


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Yooperlites of Pilanesberg

Posted by Site Moderator Webmaster on Monday, April 26, 2021, In : Mineralogy 

Willie Lombard

On the shores of Lake Superior in the USA a fluorescent rock made headlines (on YouTube, anyway!). They call the normally drab rock a Yooper, after the locals from Upper Michigan. A geologist from the local university found that the sodalite in the rock causes the yellow fluorescence. I wish my sodalite would fluoresce like that! Those that do, produce only a very weak yellowish glow.

On my way to the Groot Marico Gemboree in 2018 I decided to sleep over in the Pi...


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FLUORESCENCE IN MINERALS: A BRIEF INTRODUCTION TO WONDERLAND

Posted by Site Moderator Webmaster on Monday, April 26, 2021, In : Mineralogy 

By Peter Rosewarne

Introduction

The branch of mineralogy dealing with fluorescence apparently gained popularity in the 1930s with the availability of battery-powered portable ultraviolet (UV) lamps. The pioneer in producing such UV lamps and using them to prospect for and showcase minerals was Thomas S Warren, after whom the Thomas S Warren Museum of Fluorescence at Sterling Hill Mine Museum in the USA is named.

Those of you who have been paying attention to previous MinChat articles will ...


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