Lignite and pyrite

While out drilling not so long ago, I happened upon a unexpected layer of lignite and pyrite in the overburden.

The lignite chips were from ~160m below the current surface and came up as small, black spongy rodlike shapes with a clear woody texture. A number of the chips had positive buoyancy and would float in my rinse water. Samples above and below the lignite, appear to be a form of brown or red dolomitic mudstone as it fizzed on contact with acid. I'm leaning away from a siderite classification, as i also recovered the following:

Imbedded in the mudstone, and proximial to minor lignite, were small grains of pyrite. They sparkled like gold in the sun and had a dark streak. Siderite is prized as it is low in sulfur however the presence of pyrite indicates sulfer enrichment.

I hypothesize these rocks are the result of a significantly more humid climate where water was able to pool at the surface. In this particular location, a swamp has formed. Dead vegetation was covered by water and sediment before significant decay could occur. The anoxic environment of the swamp has preserved some of the vegetation prior to burial. The water chemistry probably has also contributed to the precipitation of sulfur as pyrite.

Sedimentary structures - mud cracks and rain droplets

Very occasionally, it's possible to find ancient raindrops preserved in sedimentary rocks. These imprints tell us a couple of things, a) the host sediment was either under very shallow water or at the Earths surface so it's highly likely to be of terrestrial (as opposed to marine) origin and b) the overlying sediment was deposited in a very low energy environment so as not to disturb the imprints.

 

The image above displays two lovely modern sedimentary features, mudcracks and rain drop craters. Interestingly, we can see that in the middle of the images the raindrops imprints get fuzzy before stopping. We can therefore assume this is the border of a puddle that existed either before the rainfall or soon after as either the water absorbed the impact of the raindrop creating no mini-crater or the water encroached and wore the imprint away.

Think about how fragile these mudcracks and raindrop craters are, they'd be erased by the next large rainfall if not covered over and protected. The likelyhood of raindrop preservation is very low, so if you do happen to find some take a moment to marvel at the numerous process that had to occur to create that rock!

Willy-willy weather

 

Willy-willy weather is here!

For those not familiar with the Australian vernacular, a willy-willy is a dust devil or small whirlwind. The word itself is an adoption from the Yindjibarndi/ Wemba-Wemba language/s. I've used it ever since I read the Silver Brumby books as a child and like most common words, my understanding of its history and original usage is sadly lacking.

A willy-willy can be small, they're often seen in urban environments where two opposing breezes meet on a street corner. They can also be quite large though I've never encountered the term being used for a Category Anything Tornado.  In Australia they can be responsible for a significant amount of sediment transport and do contribute to topsoil erosion. Areas with limited vegetation coverage, such as this recently bulldozed track, can be especially vulnerable. Sand dunes, with their well sorted and graded particles are also quite susceptible to erosion by willy-willy. The seasonable nature of these natural features should be considered when planning any earth moving activities such as rehabilitation.

Rig cookery - the humble hole plug

This blog was called Rocks and Rocksalt because my partner in crime is supposed to provide foodie reviews while I manage the rock reviews when we travel. One half of this partnership isn't pulling their weight, blog-wise. :)

Instead I present a new topic - FIFO cookery.

If you've ever worked FIFO (fly-in-fly-out) you'll understand how big an impact food can have on your life. If you are lucky, you're in a small camp with a chef who cares enough to create a varied diet on a regular basis. It seems that the larger the camp gets, the less flexibility there is. This is the case with my camp. The same provider runs all of the camps in the Pilbara and offers the same meals to everyone. The menu for dinner is highly varied (i.e. they rotate between 6 ways of serving potatoes and do try to offer at least one green vegetable each night).

The menu for lunch however, is dismal. Don't get me wrong, there is a lot of selection in the bain-marie's however it's the same, unchanging options day in day out. The cooks do try to vary the 'salads' however they always boil down to the same four selections - the Chef's special (which can be assembled from the ingredients in the other bain-maries quite easily), the oil salad, the mayonnaise salad and the inappropriate meat salad (i.e. tuna or bacon added where it isn't required). Recently we've been offered a 'special' option every second day which was often a DIY noodlebox sort of thing. Unfortunately, after about a month, this morphed into pre-packaged ham and cheese sandwiches. Not very inspiring, especially on week two of your swing.

To combat this, many people bring up their own food or have come up with a variety of ways to combine the ingredients offered to create an array of taste sensations. I'll be posting recipes and instructions at least once a month. They will assume you have access the basic ingredients and will highlight any additional item you may need to bring in from the city. Additional items will be limited because the Authors don't believe in (read: are poor at) planning ahead. I'll also break down the recipes into two categories - indoor and outdoor. Indoor will assume you have access to hotwater, ice and a sandwich press.

Outdoor cooking may require some inventiveness on your behalf. I believe people used to heat pies on the elements of lighting plants but this is a safety risk and I do not suggest this method at all. Instead, I highly recommend the use of the humble hole plug. This black container is typically wedged in the top of a drill hole upon completion and should be readily available from your drilling laydown. When sealed and left on the dash of your car in full Pilbara sun, this black-plastic wonder can reach temperatures in excess of 50 degrees (I'll science that up for you in a later post). Better yet, the hole-plug used for 140mm RC holes, can hold a standard round plastic lunch container quite easily. I highly recommend it for all your warming, baking and braising needs.

Set and forget cooking with RC hole-plugs.

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