FMF - Friends of Minerals Forum, discussion and message board

[Bob Harman]

A trip thru South Central Indiana shows geodes have uses other than usual indoor display specimens on counter tops or shelves. These pix show geodes as yard and garden decorations or as other outside decorations.

[Bob Harman]

Two more examples of Baryte from the rte 37 Harrodsburg road cuts, Monroe County Indiana. While these are geodes, they display like simple cabinet size specimens.

[Matt_Zukowski]

What is the blue on DSC03836? Celestine?

[Bob Harman]

HI MATT, The gold in Indiana celestines, I believe, is really really small micro marcasites, but not sure what the blue is. The celestines from Michigan and Ohio are also often blue, but I am also not sure what causes the blue color in all the examples. BOB

[Bob Harman]

Two more examples from the rte 56 road cuts in Washington County Indiana. The first example shows both halves and each can be also be displayed as a simple cabinet size specimen rather than a geode.

[Bob Harman]

Two more examples of Aragonite from a lakeshore locality in southern Monroe County Indiana. Most aragonite in Indiana occurs in "old" geodes along with decaying ferroan dolomite so it is noteworthy that the first example does not.

Both examples were self collected. The first one was collected in 2009 the second was collected in 2012.

[Bob Harman]

Hematite on quartz. In Indiana, quartz is largely found as crystal tips and small occasionally well formed (sometimes doubly terminated) crystals in geodes. Infrequently it is also found in quarries as druzy linings in cavities.

To my knowledge, the largest well formed Indiana quartz crystals are doubly terminated examples about 1 cm.

[Bob Harman]

Ideally acicular sprays of millerite should be free standing into the cavity of the vug or geode, but in reality many sprays are completely enclosed in surrounding calcite and rarely in Baryte. These 3 examples have been culled from Indiana geodes. The 2 on the right are within calcites and the one yellowish example on the left has been culled from a Baryte crystal.

[Bob Harman]

Another example of bicolor celestine from Washington County.

[Pierre Joubert]

Very nice specimens Bob, more so because they are self collected.

[Bob Harman]

Two additional examples. The first can be seen to include its surrounding limestone matrix.

The very freshest finds either include the matrix or are extracted from it. This example is an interesting Baryte crystal with different shaped phantoms than the final terminated crystal. The Baryte is surrounded by dolomite groupings, all on quartz. Self collected about 2007.

The second example is a well displayed large geode with complex inter-grown calcites, dolomite and Baryte. One of the larger calcites near the middle of the cavity is doubly terminated. Collected in the 1990s.

[Bob Harman]

Many forms of calcite can be found throughout Indiana. These 2 examples have well formed crystals covered by a crust. The crust is either aragonite or kaolinite.

[Jamison Brizendine]

Last weekend I attended my tenth year college reunion at Earlham College in Richmond, Indiana. I met with one of my old geology professors and several new professors teaching at the college.

I also had an opportunity to view the "rock room" where they store specimens. Unfortunately, many specimens are missing provenance information or lack any labels. The college recently hired a new curator to organize the collection and give it the attention that it needs. The fossil collection though, is meticulously organized and labeled as several professors personally collected this material.

I did find a few specimens that I thought were worthy of being photographed and shared and this was one of them that I wanted to share.

Ansel Gooding (1924 - 1976) was a geologist whose specialty was Pleistocene geology in eastern Indiana. This specimen was personally collected by him in Spring 1966. The major city near here is Louisville, Kentucky.

Considering that there are a few mineral specimens from here (or on Mindat), I thought it was a worthy candidate.

[Bob Harman]

An interesting large geode with calcites, barite and iron rich dolomite groupings. Nicely opened and very well displayed. The other half is mainly quartz.

[Bob Harman]

Experienced geode collectors can usually tell if an unopened example is hollow or solid. This is especially true if the cavity is large. Large examples with small central cavities can be difficult, if not impossible, to tell from solid examples. Hollow examples are decidedly light in weight compared to their size. What cannot be determined prior to opening the example, is the orientation of any secondary mineral crystals within the cavity. Opening the geode becomes "the luck of the draw" so to speak; sometimes the crystals remain intact and other times the break is right thru collectible crystals breaking or cleaving them. This large example had several intergrown calcites. A couple of rhombohedral crystals remained intact while one was cleaved by the opening of the geode.

[Bob Harman]

I have already shown a couple of examples of doubly terminated BARYTE crystals in Indiana geodes. Here are a couple of additional examples.

[Bob Harman]

this example was found in 2013 at the Indiana rte 56 road cuts. More of a "specimen" than a geode.

[Bob Harman]

Barite and dolomite on quartz. Acquired from Dan Weinrich minerals about 8 - 10 years ago. Not very often that I find a hi quality Indiana geode available.

[Bob Harman]

The mineral calcite, CaCO3, is very commonly found in the Midwest both in geodes and other occurrences, but the equally simple carbonate mineral rhodochrosite, MnCO3, is, to my knowledge, never found in the sedimentary environment of Midwest geodes and nearby non-geode occurrences. Manganese is otherwise rather common as its oxides including "wad". These 2 carbonate minerals must form under very different conditions.
Several Midwest geode locations, however, do host occasional finds of manganese rich calcite crystals (or manganoan calcites.....are they the same????). Sheffler's Geode Mine in Missouri is, perhaps, the best known locality. An example is shown as part of the state of Missouri mineral specimens.
This example is from Monroe County Indiana and a very rare occurrence as I have never seen another quite so pink.

[Tobi]

A very beautiful calcite specimen, Bob. At first sight, it reminded me of a pink fluorite ;-)