Dana Slaughter will discuss the geology, history and importance of the Tri-State District (Missouri, Oklahoma, and Kansas) with a photo emphasis on great specimens. It has been his favorite mineral locality since he was a kid due to the affordability and sheer tonnage of specimens available. Dana has been interested in minerals for his entire life, and he has an incredible memory and can give you unlimited information about minerals and mineral localities. He is interested in all minerals but unlike many collectors he likes dark minerals and radioactive minerals.

 Dana (left)
with part of the A.L. Flagg Collection

 Tri-State District Minerals

The Tri-State District was mined for lead and zinc and was active from the 1850s until 1970, when the last mine closed. The district has 61 different mineral species but is best known for the galena, sphalerite, calcite, and dolomite specimens. The specimens below are from the Joplin area in Missouri. If you get to the Museum early look around and see if you can find some specimens on exhibit from the Tri-State area.

Calcite on Quartz

Sphalerite and Dolomite Galena


Zeolites are aluminosilicate (containing aluminum, Al, and Silicon, Si) minerals that usually contain a large amount of water.   

This group of minerals was named in 1756 by Axel Fredrik Cronstedt, a Swedisth mineralogist who heated a mineral, which was probably stilbite, and it produced lots of steam.

For example stilbite has the formula NaCa4(Al9Si27O72).28H2O (that's 28 parts water for every molecule). There are over 40 naturally occuring minerals in the zeolite group, and more than 200 are made by industry..


Many of the specimens in this exhibit are from India, where large quantities of zeolites have been collected from basalt.

Zeolites form where volcanic rocks and ash interact with alkaline groundwater, or over a long time, even millions of years, in shallow marine basins.

In addition to forming naturally, zeolites are made by industry. Zeolite crystals have a very open structure, and they can be used for water purification and other types of filtering.



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