The Fascinating Process of Gold Formation in Quartz Veins

Summary

In this script, Bruce explores the geological processes that led to gold deposits in quartz, focusing on Western Australia's Eastern gold fields. He explains how, around 2.5 billion years ago, tectonic activity and magma chambers caused gold to rise through faults. Bruce discusses the importance of looking for iron-rich rocks, quartz veining, and signs of multiple mineralization phases to find gold. He also advises prospectors to search for laminated or brecciated quartz and to be aware of the value of large structures and GPS locations for potential gold finds.

Takeaways

• 📚 Gold mineralization in Western Australia is believed to have occurred around 2.5 billion years ago, shortly after the Earth's formation.
• 📚 Gold is often found in quartz because quartz, being less dense, rises first in geological processes.
• 📝 The geological process involves faults in the Earth's crust that allow magma and mineral-rich fluids to rise towards the surface.
• 📝 Gold is typically deposited in iron-rich rocks like greenstone belts, gabbros, dolerites, and banded iron formations due to its reaction with iron.
• 📝 Prospectors should look for quartz veining that has experienced multiple phases of breaking and reforming, indicating repeated mineralization.
• 📝 Brecciated quartz, where quartz appears broken and re-cemented with mineral-rich fluids, is a promising sign for gold deposits.
• 📝 Laminated quartz with thin black lines represents multiple phases of mineralization, which could indicate gold presence.
• 📝 The presence of iron staining in quartz, showing red, brown, or black colors, suggests gold may have precipitated out of the mineral-rich fluids.
• 📝 Erosion over millions of years has brought gold deposits to the surface, making them accessible for modern prospectors.
• 📝 Prospectors should look for large structures, iron-rich rocks, and stained quartz to increase their chances of finding gold deposits.

Q & A

What is the significance of the time period 2.5 billion years ago in relation to gold mineralization?

2.5 billion years ago is a major phase of gold mineralization, particularly in Western Australia's Eastern gold fields. This period is significant as it was not long after the formation of the Earth, and the geological processes during this time contributed to pushing gold up through the crust.

What geological structures are believed to have played a role in bringing gold up from deep within the Earth?

Faults and magma chambers were the key geological structures that facilitated the movement of gold. As the Earth's crust broke due to tectonic activity, magma chambers provided a source of molten rock that, when differentiated, allowed lighter minerals like quartz to rise first, followed by heavier minerals such as gold.

Why is quartz often associated with gold deposits?

Quartz has a lower specific gravity (around 2.6 to 2.65), making it one of the first minerals to rise through the fault zones created by tectonic activity. As it moves upwards, it can carry gold with it, leading to the association between quartz and gold deposits.

What is the role of iron-rich rocks in the formation of gold deposits?

Gold-bearing solutions tend to react with iron-rich rocks, leading to the precipitation of gold. This is why greenstone belts, which are iron-rich, are often areas where gold is found. Banded iron formations (BIFs) are also significant as they provide alternating layers of iron-rich sediments and silica that can attract gold.

What does the term 'differentiation' refer to in the context of magma chambers?

Differentiation in magma chambers refers to the process where lighter minerals and elements float to the top, medium ones remain in the middle, and heavier ones sink to the bottom, creating layers. This分层 process is crucial for the separation and eventual rise of gold.

Why are quartz veins with multiple phases of mineralization more likely to contain gold?

Quartz veins that have experienced multiple phases of mineralization indicate repeated fracturing and reforming, which increases the likelihood of gold being deposited during these events. Each phase can introduce more gold into the vein.

What are the characteristics of 'breciated quartz' and why is it significant for gold prospectors?

Breciated quartz is quartz that has been broken and re-cemented together, often with different colors indicating multiple mineralization events. It is significant for gold prospectors because the fracturing and movement of the quartz can lead to the concentration of gold within these structures.

How does erosion play a role in exposing gold deposits at the surface?

Over millions of years, erosion has worn down mountain ranges and removed layers of sediment, bringing gold deposits closer to the surface. This process has made it possible for present-day prospectors to find gold that was once deeply buried.

What advice does Bruce give for finding gold-rich quartz?

Bruce advises looking for structures with big, deep quartz veins, especially those in iron-rich rocks. He also suggests examining quartz for signs of multiple mineralization phases, such as laminated or brecciated quartz, and looking for staining that could indicate the presence of gold.

Why are GPS coordinates important when finding potential gold deposits?

GPS coordinates are crucial for marking the locations of potential gold deposits. They allow prospectors to return to these sites for further exploration and claim the area as a potential mining site.

Outlines

00:00

🌋 Geological Processes and Gold Mineralization

This paragraph discusses the geological processes that led to gold mineralization, particularly in Western Australia around 2.5 billion years ago. It explains how faults in the Earth's crust allowed magma chambers, similar to those under present-day volcanoes, to push gold upwards. The process of differentiation within these magma chambers caused lighter minerals like quartz to rise first, followed by heavier minerals such as gold. The paragraph also touches on the importance of finding structures with repeated phases of breaking and reforming, which are more likely to contain gold deposits.

05:02

💠 Quartz and Gold in Fault Zones

The second paragraph delves into the specifics of how quartz and gold are associated in fault zones. It describes the process of mineralization where lighter elements like quartz are the first to be pushed up through faults due to pressure from magma chambers. The paragraph emphasizes the importance of looking for quartz veining that has experienced multiple phases of breaking and reforming, which indicates a higher likelihood of gold presence. It also highlights the significance of iron-rich rocks in the area, as gold-bearing solutions will react with these to precipitate gold. The types of quartz veins to look for are those with laminated bands or brecciated quartz, which show signs of multiple mineralization phases and破碎的 quartz pieces re-cemented with more quartz, indicating promising areas for gold deposits.

10:02

🏔 Erosion and Surface Exposure of Gold

The final paragraph explains how the gold and quartz that were once deep within the Earth's crust have been exposed on the surface due to millions of years of erosion. It discusses how the land level has lowered as a result of this erosion, causing the once-subterranean gold deposits to become accessible. The speaker advises prospectors to look for specific signs in the field, such as brecciated or laminated quartz, and to search for structures that indicate deep chambers where gold may have precipitated out. The importance of noting GPS locations and keeping findings confidential is also stressed, as these could potentially be valuable gold deposits.

Keywords

💡Quartz

Quartz is a hard, crystalline mineral composed of silicon and oxygen atoms. It is one of the Earth's most common minerals. In the context of the video, quartz plays a significant role in the geological processes that lead to gold mineralization. The script mentions that quartz, due to its relatively low specific gravity, is one of the first minerals to rise through the Earth's crust along fault lines. It often appears as the first material to be pushed upwards during the differentiation process in magma chambers, which is crucial for the formation of gold deposits.

💡Gold mineralization

Gold mineralization refers to the process by which gold is concentrated in certain areas of the Earth's crust. The video script discusses how this process occurred approximately 2.5 billion years ago in Western Australia, with gold being pushed upwards through the crust due to tectonic activity and magma chamber differentiation. The timing and location of these events are key to understanding where to find gold deposits today.

💡Faults

Faults are fractures or zones of fractures in the Earth's crust where there has been significant displacement. The script explains that faults are crucial in the geological processes that lead to gold mineralization, as they provide pathways for mineral-rich fluids to rise from deep within the Earth. The video uses the analogy of a fault as a 'pipe' through which lighter minerals like quartz and heavier minerals like gold are pushed upwards.

💡Differentiation

Differentiation in geology refers to the process by which a mixture of molten materials, such as those found in magma chambers, separates into layers based on their densities. In the script, differentiation is described as a key process occurring within magma chambers, where lighter minerals like quartz rise to the top, and heavier minerals, including gold, settle at the bottom. This process is essential for the concentration of valuable minerals like gold.

💡Magma chambers

Magma chambers are large underground cavities filled with molten rock, or magma. The video script mentions that these chambers, located tens or even hundreds of kilometers below the Earth's surface, are the source of the mineral-rich fluids that rise to form gold deposits. Magma chambers are likened to the source of the 'good stuff' that gets pushed upwards through faults.

💡Greenstone belt

A greenstone belt is a region of the Earth's crust that contains a high proportion of greenstone, which is a type of meta-igneous rock. In the context of the video, the greenstone belt is highlighted as an area rich in iron, which is important for the precipitation of gold from mineral-bearing solutions. The script advises prospectors to look for gold in these iron-rich regions.

💡Banded iron formations (BIFs)

Banded iron formations are sedimentary rock formations characterized by alternating layers of iron-rich minerals and silica or chert. The video script explains that these formations are significant in the search for gold because when mineral-rich fluids rise through faults and intersect with BIFs, gold can precipitate out of the solution, leading to gold concentrations.

💡Quartz veining

Quartz veining refers to the presence of quartz-filled fractures or fissures in rocks. The script describes how multiple phases of breaking and reforming of these veins can lead to the concentration of gold. Prospectors are advised to look for quartz veining that has experienced multiple phases of mineralization, as this is indicative of a higher likelihood of gold deposits.

💡Breccia

Breccia is a type of sedimentary rock that consists of broken fragments of minerals or rocks cemented together by a fine-grained matrix. In the video, brecciated quartz is mentioned as a sign of promising gold mineralization. When mineral-rich fluids move through quartz, they can cause it to break and re-cement, forming brecciated patterns that may contain gold.

💡Erosion

Erosion is the process by which natural forces like wind, water, and ice wear away rocks and soil. The script discusses how millions of years of erosion have exposed gold deposits that were once buried deep within the Earth's crust. This process has led to the formation of the present-day landscape where prospectors can search for gold.

💡Prospector

A prospector is someone who searches for mineral deposits, especially gold. The video script is directed at part-time prospectors, providing them with knowledge about the geological processes that lead to gold deposits and advising them on what to look for in the field. The term 'prospector' is central to the video's theme of searching for gold.

Highlights

Quartz is often found with gold due to geological processes that push gold up through the Earth's crust.

Major gold mineralization occurred in Western Australia around 2.5 billion years ago.

Gold mineralization happened shortly after the Earth's formation about 4.5 billion years ago.

Faults in the Earth's crust allowed gold to rise from deep magma chambers.

Magma chambers are similar to those found under present-day volcanoes.

Differentiation in magma chambers causes lighter minerals like quartz to rise.

Quartz has a specific gravity around 2.65, making it one of the first minerals to rise in fault zones.

Gold, being heavier, rises later in the faulting process.

Iron-rich rocks like greenstone belts are areas where gold is likely to precipitate out of mineral-rich fluids.

Banded iron formations are also areas where gold can be found due to their iron content.

Quartz veins that have experienced multiple phases of breaking and reforming are promising for gold.

Laminated quartz with thin black lines indicates multiple mineralization phases.

Brecciated quartz, where the mineralization has broken the quartz, is a good sign for gold deposits.

Iron staining around quartz fragments is a sign of gold mineralization.

Over millions of years, erosion has brought gold deposits to the surface.

Prospectors look for structures, iron-rich rocks, and stained quartz veins.

Visible gold can sometimes be found in high-grade structures like quartz reefs.

GPS locations of potential gold sites and keep them secret for future exploration.

Transcripts

hey it's Bruce here for the part-time

prospector

have you ever wondered how quartz is

tied up with with gold and gold tied up

at the courts and why doesn't it occur

in Sandstone or something else or some

other type of rock

so

it all comes down to how did the gold

get up to where basically we're finding

at the moment so this is a bit of the

story

of my understanding

of the geological processes that push

gold up through the crust so

we're gonna go back in time about two

and a half billion years

and so that is a time that most

geologists believe there's a major phase

of gold mineralization occurring within

Western Australia occurred in different

times in different other places around

Australia and around the world but in wa

for the Eastern gold fields that runs

from Norsemen and the South to walloona

in the north and maybe a little bit

further

that is the main sort of driver is the

gold occurred around about 2.5 billion

that is with a B so it's a long long

time ago when you think of the Earth was

supposedly made about 4.5 billion years

ago this is events that occurred not

that long after the formation of the

Earth and so the Earth was quite a

different place from what it is today

there might have been some microbes

hiding some corners but there was

nothing really there was no dinosaurs

anything like that so this is a very

very horrible place

so what was driving the gold to come up

so as these structures The Faults that

were forming there was a lot of false

breaking across the continent they were

bringing up the good stuff from Below so

if we do it on the Whiteboard here just

do a very simplistic cross section

through the Earth so this is the surface

of the Earth

now none of this is to scale okay I'm

just doing this for demonstration

purposes and we've got trees growing on

the top now

just to show you that that's where the

atmosphere is and remember back in those

days there was no trees

again

down in towards the center of the Earth

it doesn't even have to be at the center

of the Earth but

at least 50 to 100 kilometers below the

surface of the

the Earth that exists at 2.5 billion

years ago there was these magma changes

magma Chambers these are similar to The

magma chambers that exist underneath

present-day volcanoes and so these are

hot bubbling

just oozing masses of molten rock just

just

waiting to explode they're into

phenomenal temperatures down there

they're talking hundreds if not

thousands of these integrated and a

phenomenal pressures yeah thousands of

of pounds per square inch if you want to

use the old thing I don't know what the

exact number is you could look it up but

it's very very high pressures very high

temperatures

and so this stuff is look just looking

for a way to get out and as soon as a

break occurs in the ground be it from

tectonic activity be it from a meteorite

impact be it from whatever the ground

breaks

and this has caused the fault that runs

along the ground now this fault doesn't

have to be a massive width it doesn't

have to be like the ones you see on the

movies where they open up and all houses

falling in it can just be half a

millimeter wide a millimeter wide maybe

a centimeter wide that's just enough

to release the pressure that's in one of

these Chambers

but one of the ancient

of these Chambers at the moment

is as it's bubbling away

starting a process called

differentiation

and that is what's happening is when you

get

lighter minerals and elements are

starting to float to the top medium ones

in the middle and heavier ones at the

bottom

and so it's a bit like you know oil and

water oil floats above there is lighter

it floats above the water and so you get

these layers occurring around the

outside now nothing to scale here

so you've got a lot of stuff at the top

heavier stuff at the bottom

and it's just sitting there waiting to

go

a fault comes along

for whatever reason hopefully you can

see this blue

and it it occurs and it does not have to

reach the surface vast majority of the

time it never reached the surface and

this could have stopped

tens or more kilometers below the

surface so 10 plus kilometers below the

surface is this point here

because when this high pressure

liquids and gases down there is that

sorry it's liquids inside there's no gas

down there high pressure liquids finds

this zone of low pressure

is that it starts to immediately race up

the crack

so it starts bubbling its way up and

pushing it and as it pushes this way up

this zone of weakness this fault Zone

it's applying phenomenal pressure and a

nominal effect on the surrounding rocks

and it's pushing these rocks apart

pushing them and the more it pushes the

part the more that it sucks up stuff

from down the bottom

so the first stuff that's going to zoom

up this full plane is going to be the

light stuff

and what is the light stuff you guessed

it quartz quartz is an SG or specific

gravity around about 2.6 2.65 and it's

one of the first things to zoom up the

pipe so as it zooms up it's going up up

the system here pushing apart pushing

and pushing and pushing apart and

actually reacting with the the

surrounding rocks

if there's a subsequent phase of

mineralization or faulting

okay now this is the key one part here

if this subsequent phases the next

heavier stuff starts to go up the pipe

and there's another event more heavier

stuff things and the last stuff to go up

the pipe I'm calling it pipe but I mean

go up the fault zone is there heavier

stuff the heaviest minerals going up and

what is the heaviest minerals the

heaviest mineral that you and I are

interested in Gold that's when it goes

up so what we want to find is a

structure

let's head repeated and multiple

breaking and reforming and more

um quartz and minerals been ejected in

and over and over and over and over

again and the more times this happens

the more likely is we're going to get to

the stage where the heavy stuff was

brought in

but this rock is not uniform in in

composition there might be some you know

best Ultra one bit granites and another

bit and so on like this but if you've

got a band for example

of iron-rich rocks

dollar rights and something like that

even basalts okay they are iron rich

the the courts the the the fluids coming

up bearing goals gold will start to

react with the iron rich rocks

this is why we fight we tell everyone

when you're going out looking for gold

look at the greenstone belt because the

greenstone belt is iron rich rocks it is

the the the the the gabbros the dollar

rights the uh the basalts

and also look in the banded iron

formations

okay so the banded ions are alternating

layers of iron-rich sediments with

silica and chert and back and forth it

keeps alternating and so if this is a

zone of banded iron or Biff

sometimes you show it on a um on the um

geological map as a Sif s i f stands for

sedimentary iron formations basically

the same stuff

the the goal-bearing solutions will be

racing up the fault intersecting this

iron rich thing and start to precipitate

out of of um of the solution and so what

and what you end up having is

concentrations of gold in here

and minor concentrations of gold along

here

so

what we're looking for when we get out

there

is we want to find iron rich girl iron

rich rocks

we want to find quartz veining

and we want to find quartz veining

that's experienced multiple phases of

breaking and reforming and researmenting

and breaking again and more minerals

coming in so so what does that rock look

like we all know what the the classic

white quartz blow looks like looks white

like the snow almost it's hungry quartz

basically as as we used to call it

hungry courts has nothing in it it's

basically that first lot of stuff that

came up and nothing followed up

what we won't look for is quartz that if

I draw a zoomed in layer of a quartz

vein here this is quartz country rock on

their sides and so the next layer of of

injection of mineralized bearing fluids

will either come up along the edges

and we'll start seeing laminated bands

sitting near the edges of the courts so

you may be a a baron inner core my

bearing has an almost solid white and

they're and they're hanging wall

football areas will be laminated and

they can be very close together we're

talking maybe millimeters apart to maybe

centimeters apart usually no more than a

few centimeters apart and they thin

black lines in the courts each one of

those thin black lines represents a

phase of mineralization coming in and

the more of these black lines you got

he wrote the more phases of

mineralization there was but that that

one form of mineralization occurs and

that generally occurs down towards the

southern end of the gold Fields down in

Norseman for example there's a mine down

there and fortunately closed in the

1990s

but they pull them more than a million

ounces out of this quartz Reef I was

about between one and two meters wide

and it ran more than an ounce per ton

and that ran like that for Neti oh I

don't know started in the 30s and wound

up in the 90s so what's that 50 to 60 is

so there was a lot of gold in that

system they're just sitting in these

laminations

the other type of mineralization to keep

an eye open for and this is a somewhat

more common one is that as the

mineralization comes up it starts to

break this quartz

and so you get the sort of change colors

here you get this sort of pattern all

over the thing I've just broken quartz

you must probably seen it around it's

called brechiated quartz

and so the mineralization is coming up

and as it comes up it moves from around

each one of these rocks and these little

it almost looks like

um looks like

concrete with not much cement in it just

a lot of rocks that have been slightly

moved apart and re-cemented together

with more quartz or generally what we're

looking for is a lot of iron around

these these quartz bits this quartz

fragments and so the more iron that's in

the system and the same thing up here

the more iron they got pumped up the

more likely that gold is going to

precipitate out so that more busted up

you can see the quartz and the more iron

staining so that's the Reds the Browns

sometimes into the blacks

that is the good mineralization that's

coming up so if you bust a bit of rock

quartz open and inside and the fresh

broken faces you can see all these sort

of broken up pieces resemented together

with all sorts of different colors in it

this is looking really promising

now as the time went past

you know as I said this is may have

stopped 10 10 kilometers below the

surface so you may be wondering well how

did that how did that quartz get on the

surface now that we can metal detect it

well simple little process called

millions and millions and millions of

years of erosion Australia is one of the

most geologically stable countries in

the entire planet and not much has

changed for millions of years and so

what has happened is that huge mountain

ranges have just been eroded away and

dumped into the sea and so what is

happening is now the land level is down

here somewhere tens of kilometers of

sediment has been washed off the

continent and dumped into the sea you

can only guess how much gold has gone

dumped into the seam

and so now this stuff is now poking up

through the surface and this is what us

as present-day Prospectors and as past

Prospectors have been trying to find so

keep your eye open for this magic

breachier quartz

or look for the laminated quartz and

keep an eye open so what you're looking

for the all together is we want

structures big structures the longer the

structure it is the more deeper it goes

It goes all the way down to these

Chambers short look quotes especially if

you're looking at geological maps don't

go deep

okay so you'll want big structures you

want Iron rich rocks you want quartz

veining and when you get out there pick

up the quartz and have a look if it's

nice and white to the color of this

white board maybe time to move on to the

next next bit but look for the quartz

that is stained colors

break it open is the color inside the

rock or just on the outside which is

maybe present day weathering is put it

on

so look for those the things then if

you've got broken up quartz laminated

quartz look inside that you may be lucky

enough to even see a visible gold

and so um it can get the very high

grades in these sort of structures say

ounce baton sometimes multi-anses

patanum there's a lot of voids in there

for the gold to precipitate out so keep

an eye open for that

if you find that in the field

you know GPS that location because you

want to come back to it over and over

and over again grinut

Miller checked as much as you can and

keep it under your hat because this

could be a bonanza shoot

hopefully that helps you