What were the old costeans use?

[Brumble-Gum]

Hi all

Today I found a new gold bearing area that has a couple of mine shafts heading horizontally into a hill. I have followed the scattered quartz seam over a few hills, all along were the old timers costeans (Shallow horizontal trenches about 6ft deep and vary from 10ft to 50ft long). All these were running parallel with the seam a few hills over.
I was taught that shallow costeans were trenches that were dug at 45 degrees to intersect and relocate these seams/saddles further over or to determine the width of a quartz seam.
Could I have been taught wrong? Or have I found a goldfield that had too many goldtop mushrooms growing around at the time.
All ideas on these would be appreciated.

 

[loamer]

As a general rule, the cutting at angles is right however, that's working on the assumption that the diggings follow a logical sequence, that is follow up, loose or miss lead, cut suspected lead at right angles, away they go again. At times they cut where they thought and in this case it sounds about right. Also depends on when on a time scale the costeans and shafts relate to each other. For example, they could be years apart and not the same crew having a crack. At times you will see a costean dug down from a reef, saddle etc as the old boys may have been onto a small leader. Remember, the quartz (underground) looks like a tree with branches and the leaders can run in any direction from the main quartz lead. I have seen costeans that form a V a W etc. As an example, the Slip Up Lead near Tarnagulla Vic took a 90 degree turn east (hence the name) and the old fellers lost it completely and dug trenches everywhere to find it (they did). So, the costean follow general rules only - they are in my opinion a good sign. I have dug two in my time following a quartz lead that had blue slate and rotten quartz as the indicators. It is hard going and I always think that they were not mucking around. (Love the goldtop mushrooms - more likely bad booze from a sly-grog seller)

 

[Roscoe]

I thought costeans were to sample the quartz reef to see if the gold was increasing or decreasing in value as they followed the seam? But, i will be honest that is only my interpretation of what i see in the gold fields not fact. I would be interested in knowing as well Brumble-gum

You must posted that loamer when i was typing.

 

[Roscoe]

Loamer do you have a picture of a costean. Just wanted to see if what i thought was a costean is a costean.

 

[loamer]

The strict definition is to "search after lodes". Mindata says "A trench cut across the conjectured line of outcrop of a seam or orebody to expose the full width." the Master of loaming Mr Sam cash says they were for people who had no "knowledge of the right procedure for locating deposits". The King, Mr Idriess, refers to it as trenching and says it is 'trying to cut the reef'. Idriess states "If it (the reef) runs anywhere on the hillside crosswise to you, then you must eventually cut it. As you trench (costean) you will very likely strike quite a number of leaders or reefs." There are a couple of definitions, Cash disagrees with Idriess and we see on the ground no pattern at times.

One thing with them is that Cash states that when digging loaming holes, if the colour is regular and gets better at depth, by default you will continue digging down and across and what started out as a loaming hole ends up as a trench and for all intents and purposes - hey presto - a costean.

 

[loamer]

Yes mate - follow link - its down the page a bit. In this picture you will see recent drilling caps in the costean by a mining company sampling some very good ground and at the end, the trench opens out because the old fellas found the run. (FYI - assay was good - cost and profit neutral - no more digging. rehab would have eaten the profits pronto).

https://www.prospectingaustralia.com/forum/viewtopic.php?id=2042

 

[loamer]

Just one more bit from Idriess that may explain trenches that don't follow the general pattern "Should you run your trench right out and not locate the reef, come back to where you got your last loam prospect and trench at right-angles to the first trench." He also says "Don't throw your shovel in the air and yell that you are made."

 

[Brumble-Gum]

Thanks for the info loamer I thought that was the case. The old fella who taught me hasn't been wrong when it comes to groundwork and researching an area.
Cheers.

 

[MJB]

A very interesting read...but I'm bloody confused. All this dig a trench at this angle and that

Is there any chance of someone having a picture of a general trenching area so we can see were the trenches are supposed to go?

Cheers,
Matt

 

[loamer]

MJB - there is no correct answer is the answer. The trenches were generally cut at right angles, that is across a suspected 'line' of a lead. think of a cross, a long line with a shorter line across. The old diggers took a bearing from the run of diggings, which usually follow a line and headed upslope. They were hoping there would be a primary (in situ) gold deposit at the higher ground, a quartz blow, a small quartz reef etc. You will see at times an open cut dig that stops, they have started following a line of gold. The line stops and they are then searching for a continuation, hence the right angle cut. They can be anywhere at any angle and any size from small little trenches to big trenches. At times they may not be seen at all because the old fellas hit the lead again with a costean and away they went. Further, we have 150+ years on some fields in Vic of people having a crack so the diggings at times may be from the depression era etc. Suffice to say, costean trenches are a good sign, no matter what the location or layout.

Why across or at angles? because they pretty well knew the line had stopped going in the suspected direction. The trench gave them a better chance of hitting a direction changing lead-same as we never ever detect in a straight line going up a hill - too prescriptive and lessens that chances of crossing a gold 'fan' from the source origin. (The pattern of gold being shed from the 'top' of the hill.)

 

[casper]

Be sure to detect any mullock heaps associated with a costean - this 31gm nugget came out of one on the south side of Secret Hill at Waanyarra.

I didn't dig it - it was a new chum who i was advising.

 

[loamer]

very nice Casper. There are no hard and fast rules but generally downslope from the costeans has been my best finds. coincidence probably.

 

[deepblue]

I love Secret Hill I've managed to get more then my fair share of gold out of that area. My father pulled a 17 gram piece out of the track near the big gum tree a many of years ago. Most people just seem to believe that it's flogged but careful detecting pays off. One time there was a caravan setup in the clearing for a couple of weeks after they had gone I managed to get 9 pieces from where they had setup. Remember to also detect the creek bed that runs through there great place to pick up the sub grammers after the rains.

 

[TenOunce Tone]

This is a scan straight from Idriess "Prospecting for Gold"

Pretty clear to what it is all about, although he refers to trenching. This is the same thing.

The rest of the last paragraph over the page..
"your last loam prospect and trench at right-angles to the first trench. That reef may run parallel to the trench already cut.

He then goes on about tin reefs

Here is a pic i found on the net.. the grey lines are the trenches dug hoping to follow/find the reef

RNGT01 is nearly at right angles, this is what Idriess and Loamer are describing, the parallel trench may have been dug due to no luck find the reef at right angles.
Hope this help clear things up.

Cheers, Tone

 

[loamer]

I love Secret Hill I've managed to get more then my fair share of gold out of that area. My father pulled a 17 gram piece out of the track near the big gum tree a many of years ago. Most people just seem to believe that it's flogged but careful detecting pays off. One time there was a caravan setup in the clearing for a couple of weeks after they had gone I managed to get 9 pieces from where they had setup. Remember to also detect the creek bed that runs through there great place to pick up the sub grammers after the rains.

The bloke with the Eureka Flag? was up there for ages on 'his' patch. Silly old duffer - mad as a snake. the DSE just about had to bulldoze him of the site.

 

[deepblue]

There's another camp out the back of Amherst that's a bigger mess then any I've see.

 

[MJB]

Thanks Tone and Loamer, that definitely clears things up a bit. That picture says a thousand words. Makes you wonder how hard going it must have been for these old timers digging trenches all over the place in the "hope" of finding the reef. How many did not find it or found a "duffer"? Also makes you think how easy it would have been for them to miss the gold bearing reef and how many of them are still undiscovered...

Cheers for the info,
Matt

 

[Roscoe]

Thanks fella's, Looking at it know what i thought was a costean isn't a costean. I mainly see round pits dug into the reef line? The only costeans i have seen are modern excavator dug costeans. Whether they are opening up old costeans i don't know? One things for sure i know and understand what a costean is now and what to look for out in the field, thanks roscoe.

 

[argyle]

You have to take Ion Idriess with a grain of salt.

He was big noting know it all journalist, and a pathological liar who plied others for information, while claiming it by his own authority.

Costean's are dug merely as a deeper form of loaming. Cash is my man...

 

[loamer]

You have to take Ion Idriess with a grain of salt.

He was big noting know it all journalist, and a pathological liar who plied others for information, while claiming it by his own authority.

Costean's are dug merely as a deeper form of loaming. Cash is my man...

What are you basing these observations of Idriess on?

If Cash is the man, I better rip up my 1894 Miners Handbook, not to mention my Brough-Smyth collection. What do they know about costeans/trenching?