alluvium
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SWright
Steve Wright
Hi
Aluvium is a noun - it material deposited by water, in a stream, river, lake etc and that material has not been consilidated into a rock or otherwise modified. Alluvial is an adjective - such as in "this is an alluvial deposit". This is not to be confused by terms such as elluvium or elluvial, which is material not deposited by water and generally refers to material that was been weathered of rocks and deposited like on the slopes of hills. You will oftern also find elluvial gold deposits weathered from reef systems. There are also other terms that relate to weathering, soil and rock formation that I will not do into here. Hope that helps. So yes gold and many other ore minerals occur in alluvial deposits.
araluen
Aluvium is a noun - it material deposited by water, in a stream, river, lake etc and that material has not been consilidated into a rock or otherwise modified. Alluvial is an adjective - such as in "this is an alluvial deposit". This is not to be confused by terms such as elluvium or elluvial, which is material not deposited by water and generally refers to material that was been weathered of rocks and deposited like on the slopes of hills. You will oftern also find elluvial gold deposits weathered from reef systems. There are also other terms that relate to weathering, soil and rock formation that I will not do into here. Hope that helps. So yes gold and many other ore minerals occur in alluvial deposits.
araluen
SWright
Steve Wright
Ah, that's another thing. Alluvial deposits and alluvium are not necessary always associated with modern rifver systems. Older ones where the river has changed direction or the riveritslef has been filled in by volcanic rock are quite common. You can even get alluvial deposits on what are now the tops of hills. You define an alluvium by not only how it was formed but by what it contains. So if you have unconsolidated or semi consolidated material or even conglomerate in very old alluvial systems made up of cobbles and sand and all the material you would find in any modern alluvial system then it is an alluvial deposit. Take for excample the deep lead mines in Victoria or even the very ancient alluvial systems in the mines I worked in in South Africa. It can get very confusing.
araluen
araluen
essentially alluvium is detritus moved by water, rivers, creeks, floods so can include tress, rocks, mud clay, soil minerals etc. derived from alluvium is alluvial deposits. an alluvial deposit is a concentration of the minerals rocks, clay etc that have formed from a rivers movement.
Then you have eluvium that is derived from the weather, wind, mountain undulation/breakdown plate movements and gravity which causes elluvial deposits you will hear this referred to as leaching or eluviation in most text books or geo reports.
I hope that explains it someone else might be able to answer it better than me.
Then you have eluvium that is derived from the weather, wind, mountain undulation/breakdown plate movements and gravity which causes elluvial deposits you will hear this referred to as leaching or eluviation in most text books or geo reports.
I hope that explains it someone else might be able to answer it better than me.
your too quick SWright 
Wow
I think you two just added confusion to the term, basically your both right, but I would stick to the definition that alluvium is material that have been eroded, transported and deposited by water. Some of the stuff you mentioned is not alluvium, i.e. conglomerate, which is alluvium metamorphosed by the inclusion of a binding agent such silicate, which then if becomes classified as a rock.
And really, the answer to your question thebeans, is yes alluvium is the host for the majority of deposits, and most definitely take samples. Couple of simple rules for your process,
1. Remember that gold is heavy and generally will settle furthest down.
2. If you have a gps, take a waypoint at each sample location, and take your sample with the same number, if it's good you ll know exactly where to return to.
3. to basically assay, (get a measure on the value of an area), your sample size needs to workable, a 20l bucket sample is a good measure, 40 buckets equals a yard.
4. With point 1. in mind, remember to dig a little deeper for your sample, a good indicator of auriferous (Gold Bearing) zone, is if you find what is determined as wash, this will be a layer of gravels in the area.
5. SWright is correct in what he says about, alluvium deposits and courses that streams can take over the years, but be mindful that these elevated deep leads etc, were developed more then likely up to 1500 million years ago. Look the inside corner of any water course in your area, this where the water flow will have lost momentum, and subsequently dropped its load.
Good luck
I think you two just added confusion to the term, basically your both right, but I would stick to the definition that alluvium is material that have been eroded, transported and deposited by water. Some of the stuff you mentioned is not alluvium, i.e. conglomerate, which is alluvium metamorphosed by the inclusion of a binding agent such silicate, which then if becomes classified as a rock.
And really, the answer to your question thebeans, is yes alluvium is the host for the majority of deposits, and most definitely take samples. Couple of simple rules for your process,
1. Remember that gold is heavy and generally will settle furthest down.
2. If you have a gps, take a waypoint at each sample location, and take your sample with the same number, if it's good you ll know exactly where to return to.
3. to basically assay, (get a measure on the value of an area), your sample size needs to workable, a 20l bucket sample is a good measure, 40 buckets equals a yard.
4. With point 1. in mind, remember to dig a little deeper for your sample, a good indicator of auriferous (Gold Bearing) zone, is if you find what is determined as wash, this will be a layer of gravels in the area.
5. SWright is correct in what he says about, alluvium deposits and courses that streams can take over the years, but be mindful that these elevated deep leads etc, were developed more then likely up to 1500 million years ago. Look the inside corner of any water course in your area, this where the water flow will have lost momentum, and subsequently dropped its load.
Good luck
Village said:
I think you may have confused yourself
alluvium refers to the sedimentary deposition and certainly can inckude conglomerateHey the beans
To get a better understanding of geology as whole, the "Geology for dummies" isn't a bad introduction into the field. It will give you the basics and a sound grounding in the varnacular used in the field.You have to keep in mind geology like medicine has many specialists fields. If your going to use geo data bases, this book will provide you with the information to under standard the vast information that will be displayed.
Don't get me wrong on the Geology for Dummies, trust me as intro, this book is probably the best. Most text are written to support a course of study in which you have available to you, teachers, professors and hands on samples to further develop and build on the information. An additional resource, if it's still available, was Geology Kitchen on you tube I think. The guy uses food and the kitchen to demonstrate the theories that under pin the subject.
Youtube is free, Geology for Dummies, I m not sure say $30 to $35 bucks.
To get a better understanding of geology as whole, the "Geology for dummies" isn't a bad introduction into the field. It will give you the basics and a sound grounding in the varnacular used in the field.You have to keep in mind geology like medicine has many specialists fields. If your going to use geo data bases, this book will provide you with the information to under standard the vast information that will be displayed.
Don't get me wrong on the Geology for Dummies, trust me as intro, this book is probably the best. Most text are written to support a course of study in which you have available to you, teachers, professors and hands on samples to further develop and build on the information. An additional resource, if it's still available, was Geology Kitchen on you tube I think. The guy uses food and the kitchen to demonstrate the theories that under pin the subject.
Youtube is free, Geology for Dummies, I m not sure say $30 to $35 bucks.
G0lddigg@ said:Village said:
I think you may have confused yourself
No, no confusion, Conglomerate is a sedimentary rock, that comprises of clasts of other pebbles, pebbles ideating that the composition material has travelled some distance in water, who's percentage of composition of the rocks meets or exceeds 80% in volume, held in place, cemented. Normally tertiary or age. It has a matrix and must consist of pebbles, rounded of 2mm to 10mm. Conglomerate, in addition the cementing process usually requires pressure, metamorphic process.
At real terms Alluvium refers to the method of carriage, and if associated with an additional word describes, the method carriage and the placement, ie. Alluvial Fan, Alluvial terrace, and so on.
So loose gravels or cobbles, fine sedimentary deposits, so on, are referred to alluvium, as the method of carriage was water borne, nothing more. Deposited by water.
So conglomerate is rock, formed post transportation of the material. You can have an alluvial deposit of gravels with interlaced mud and clay silts, this may have matrix, but fails the basic definition of rock, being a hard, compacted material with coherence of some form, which the materials are derived naturally.
Of course conglomerate is a rock often confused with breccia, who's clasts are angular, indicating little or no travel. All goes to defining the location of the source.
So in application,
if you find gold in conglomerate, not so an irregular occurrence, if the clasts consist of round pebbles you can determine that the origin of the bed load, transported, travelled a considerable distance before deposition. If angular, not so much walking.
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Alluvium (from the Latin, alluvius, from alluere, "to wash against") is loose, unconsolidated (not cemented together into a solid rock) soil or sediments, which has been eroded, reshaped by water in some form, and redeposited in a non-marine setting.[1][2] Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel. When this loose alluvial material is deposited or cemented into a lithological unit, or lithified, it would be called an alluvial deposit.
The term "alluvium" is not typically used in situations where the formation of the sediment can clearly be attributed to another geologic process that is well described. This includes (but is not limited to): lake sediments (lacustrine), river sediments (fluvial), or glacially-derived sediments (glacial till). Sediments that are formed and/or deposited in a perennial stream or river are typically not referred to as alluvial.
Direct from - wait for it - Wikipedia!
The term "alluvium" is not typically used in situations where the formation of the sediment can clearly be attributed to another geologic process that is well described. This includes (but is not limited to): lake sediments (lacustrine), river sediments (fluvial), or glacially-derived sediments (glacial till). Sediments that are formed and/or deposited in a perennial stream or river are typically not referred to as alluvial.
Direct from - wait for it - Wikipedia!
penfooey said:
Thank God for that. Now we have identified the problem, and in all seriousness, in every 101 subject in the science department at uni, they tell every class, "do not rely or quote from Wikipedia. The information is not in most cases, either peer reviewed or supported. In geology like most science fields there are texts and references accepted, for definitions McGraw Hill publish the Dictionary of Geology and Mineralogy, this is general accepted here, the USA and the Uk. In addition if you want to diverse into sedimentology, you should borrow or buy a copy of Gary Nichols, Sedimentology and Stratigraphy. Both books are in the second or may be third edition now.
Very good references and for the keen prospector, a must have for interpretation. I try not to diverse to far into the nomenclature, so as not raise confusion, and in the same, I only commented as the information provided, to what was a simple question, was flawed, and should a person go, with the idea or foundation built on the same, then they would be wasting their time.
It is illustrations such as this, why the internet can be a dangerous thing, words with comment and practical experience often lead to wrong directions.Wikipedia is media aimed at enthusing further research, to feed the inquiring mind, not every to be quoted.
guessing you were a teacher village?
No G0iddigg not at all. but at one time a bloke may have done study at uni. Guys I don't like correcting anyone to be honest, and most often I refrain. Sometimes where someone has an interest, and like in this case, the information sown, at the base level, if it's not correct, then how that person interrupts and applies that information, forever more, would be just as bad as an uncompensated compass, and when your looking for a needle in wash pile, well you would know the feeling, prospecting for gold does it to all of us.
I wish you all the best of the season and happy prospecting
I wish you all the best of the season and happy prospecting
Um just a point in application when you are prospecting a alluvial deposit
Like with the difference between Conglomerate and Breccia. If you find areas that consist of angular rather rounded pebbles and cobbles, and the section will contain even larger similar rocks or even boulders, this is defined as colluivum, or scree. Which is the result of erosion causing a slide, generally in the immediate are above the deposit. very low probability of being auriferous.
Here's trick I didn't learn at uni, but by my grandfather. If your prospecting an alluvial deposit and find colour in alluvial rocks, and want to trace back to the lead area, look for like samples of the auriferous rock on the hillsides, these samples need to be of angular deposition. Take a bucket home, throw in a concrete mixer with three times the volume of water, place a measure wheel fixed to the outside of the drum, and tumble the rocks until they match your auriferous sample.
Take the cumalative distance of the wheel an times it by 1.6, this allows for the more aggressive action of the paddles in the drum, and you should be somewhere in the area. Worked for him quiet well. took days and days, but beats searching aimlessly.
Just a tip, cause I note a few people are interested in tracing back to the source.
Like with the difference between Conglomerate and Breccia. If you find areas that consist of angular rather rounded pebbles and cobbles, and the section will contain even larger similar rocks or even boulders, this is defined as colluivum, or scree. Which is the result of erosion causing a slide, generally in the immediate are above the deposit. very low probability of being auriferous.
Here's trick I didn't learn at uni, but by my grandfather. If your prospecting an alluvial deposit and find colour in alluvial rocks, and want to trace back to the lead area, look for like samples of the auriferous rock on the hillsides, these samples need to be of angular deposition. Take a bucket home, throw in a concrete mixer with three times the volume of water, place a measure wheel fixed to the outside of the drum, and tumble the rocks until they match your auriferous sample.
Take the cumalative distance of the wheel an times it by 1.6, this allows for the more aggressive action of the paddles in the drum, and you should be somewhere in the area. Worked for him quiet well. took days and days, but beats searching aimlessly.
Just a tip, cause I note a few people are interested in tracing back to the source.
penfooey said:
unbelievable
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