Sand from Thermal City Gold Mine

Returning from Thermal City Gold mine yesterday and spending most of the day learning how to get rich from panning gold.  The science behind of gold panning is based on the gold density.  After stirring up the gold containing sand, the heavier gold will sink to the bottom while other materials will stay on the top.   The process involved in continuous removal of lighter sand on the top and eventually the heavier gold will become more concentrated.  I heard from staff there are plenty of microscopic gold in the sediment.  I brought home a bag of sand from the last stage of panning which contains plenty of black sands (Magnetite) and hopefully some microscopic gold in there.

Figure 1 The remaining sand of the last step of gold panning process contains very high percentage of black sand.  Many of the black sands are in fact Magnetite, an ferromagnetic mineral with chemical formula of Fe₃O₄.  Some green colored crystals are olivine, an magnesium iron silicate with the formula of (Mg,Fe)₂SiO₄.  I suspect the the pink colored crystals are rubies which are also found in the area.  Of course, the majority of the colorless crystals are quartz which is the most common mineral in the sand.

Figure 2 WE FOUND GOLD!! These are the two pieces I found in my last pan.  It would have been such a big disappointment without finding any gold during the field trip.  The length of the gold is about 1mm.  That’s the size that most of us found.  Some of the folds do find some flakes about 3-4 mm.

Figure 3 A piece a mica in the sand.  Lots of people mistake these as gold due to their metallic reflection.  They can be easily distinguished from gold because they change the reflection when looked from different angle.

		Minerals from Thermal City Gold Mine VIEW SLIDE SHOW DOWNLOAD ALL

Granites from Vulcan Material Company Kennesaw Granite Quarry

Vulcan material company's Kennesaw quarry supplies granites or granite related materials for industries and local construction. To make granite for available for it's application, the size needs to be reduced by blasting, crushing with a metal weight, crushing with jaw crusher then going through various sorters to separate different sizes.  The query is currently mining below 600 feet deep but the location we visited is at the upper level.  The appearances of the granites collected from the location varied greatly according to their compositions: quartz, mica, feldspar and amphibole.


Vulcan Kennesaw quary granite



 

This piece of rock is very soft and easily crumbled in my hand.  Some flaky
mineral were shining under the sun light.  My daughter called it fool's gold.
Under a stereo microscope, they are flaky, like micas)







Crystals of quartz (white) and micas (black) Granite under
stereo microscope. 

This piece contains feldspar (pink)

a red strip on a piece of granite.

Stilbites were find in the cavity of a piece of granite  It seems to be a nice piece for making micromount.

Staurolite Collection Field Trip to Marble, North Carolina

Staurolites crystals can be collected from the river next to the

pacesetter camp

The name Staurolite is derived from the Greek, stauros for cross and lithos for stone in reference to the common twinning. A special property of staurolite is that it often occurs twinned in a characteristic cross-shape.  Staurolite crystals has a Mohs hardness of 7 to 7.5 and a rather complex chemical formula: (Fe,Mg,Zn)₂Al₉(Si,Al)₄O₂₀(OH)₄ With Iron, magnesium and zinc occur in variable ratios.   Macroscopically visible staurolite crystals are of prismatic shape. They are often larger than the surrounding minerals and are then called porphyroblasts. 

The middle of the river has plenty of

larger rocks.  They need to be

removed be

An official field trip of Gem and Mineral Society of Franklin, NC brought us to the Pacesetter camp in Marble, North Carolina to collect Staurolite.  Staurolite can be found in the river next to the camp.  The water was mostly shallow except one area where the water was become stagnant.  There are plenty of big rocks on middle of the river bed.  They need to be removed and get to the pebble and sandy layer.  Scoop up a shavelful of the gravel or sand and place them in the screenbo.  Allow smaller sand and pebbles to go through the screen and carried away by the river.  The Staurolite crystals are larger and retained on the screenbox (Instruction for making screenbox).

The 1/2 inch mesh screenbox

The staurolite crystals collected from the middle of the river are more rounded in shape because of the tumbling effect from the river while the staurolite crystals collected from the size of the river tends to be more angled.  Belows are the Staurolites collected from the field trip.

The twinned Staurolite crystals are the most saught after form.  I collecte each one of them in the field trip.  They are collected from the middle of the river so they are very short and rounded.

Twinned staurolite crystal crossed in ninety degree angle.

Twinned staurolite crystal crossed in sixty degree angle.

Most Staurolite Crystals are not twined

Staurolites under stereo microscope.  The color of Staurolite

can be any where from brownish to black.





In thin sections staurolite is commonly twinned and shows lower first order birefringence similar to quartz, with the twinning displaying optical continuity. It can be identified in metamorphic rocks by its swiss cheese appearance (with poikilitic quartz) and often mantled porphyroblastic character.  This will be my next project.

PS. After couple days since my first collection of pond water.  Most pond lives are mostly disappears.  They were either died or go into hibernation.  I am thinking it either lack of oxygen or energy.  Summer is the season for observing pond lives.  I will postpone the making of thin section of staurolites until the summer is ended.

The Beach Sand of the Gulf of Mexico under Polarized Light Microscope

Siesta Beach is known as one of the most beautiful beaches in the world. At the "Great International White Sand Beach Challenge" held in 1987, it was recognized as having the "whitest and finest sand in the world."  The sand is so reflective that it feels cool underfoot even on the hottest days. What's the reason? Siesta Beach's sand consists of 99% quartz.

Quartz possess birefringent property which can be examined under polarized light microscope. It can provide an important clue for mineral identification.  The pictures below are the sand collected from the camping trip alone the Gulf of Mexico.  

Siesta beach sand at 20x under polarized light microscope.  The size of the
sands are small and uniform.  Under polarized light microscope, they exhibit
various colors due to different thickness and orientation.

 



Siesta beach sand at 50x under polarized light microscope

 

Crescent beach sand at 20x under polarized light microscope.  Like the
sands collected from Siesta beach.  The sizes of the sand crystal are small
and uniform.

Turtle beach sand at 20x

Sand collected from Henderson Beach, FL

Sand collected from Gulf State Park, AL

The Beach Sand of the Gulf of Mexico

The beaches on the Gulf of Mexico are famous for their crystal clean water and sugar white sand.  Siesta key beach received numerous awards for its soft, clean, pure-white sand.  The Siesta beach ranks the number one beach in Dr. Beach's top 10 beach list again this year.  Unlike most beaches that are composed of crushed shells, rocks or lava, the powdery sand found on the Siesta Beach is pure white and finer in texture than most refined sugar. Harvard University's geology department found the sand of Siesta Beach was 99% pure quartz.
During the spring break, we had a chance to visit several beaches on the Gulf of Mexico on a camping trip.  We collected some beach sand from each park on the trip (Figure 1): The Gulf State Park, Alabama, Henderson State Park, Florida and Siesta Key, Florida (We visit all three beaches on the key: Siesta, Crescent and Turtle beach).  I check them out on my microscope.  Are they as good as claimed?

Figure 1. Beach sand collection sites on our camping trip

Figure 2. Sand collected from Siesta Beach, FL

Of all beaches on our camping trip, the sand on the Siesta beach appears to be the whitest.  The sand is also very soft to touch.   It has powdery feel when I rub them between my figures.  The images under the microscope explain the the color and soft touch.  The sand crystals are almost all quartz and completely transparent with very few impurities.  The small and uniform in size also explains the powdery and soft touch.  (Note: The images under the microscope are sparkling. It looks much better than the pictures show - To be fairly compared with other sand specimens, I fixed the ISO and exposure time while taking the picture.  The whiteness of the sand caused the picture to be over-exposed.)

Figure 3. Sand collected from Crescent Beach, FL

On the same key as the Siesta beach, the Crescent beach is slightly to the south of Siesta beach.  The color of the beach sand is almost as white as the sand on Siesta beach and have the same soft, powdery feel.  Under the microscope, they appears almost the same as the sands from Siesta beach.  The slightly more yellowish color is barely noticeable unless I put the picture side by side.

Figure 4. Sand collected from turtle beach, FL

The turtle beach is located on the south end of the Siesta key.  The sand is very dark and  coarse.  There are plenty of sea shells on the beach.  There is no surprise to see that there are plenty of sand made of sea shells.   There are very few quartz crystal found in the sand collected from Turtle beach.

Figure 5 Sand collected from Henderson State Park, FL

Henderson State Park beach is located between Pensacola and Panama city.  The area is famous for its Emerald green ocean.  The sand is sugar white but the sand crystal is more granular than the sand collected from Siesta or Crescent beach.  Like the Siesta or Crescent beach, the sand is almost completely consist of transparent quartz.  The quartz crystal is also larger.

Figure 6. Sand collected from Gulf State Park, AL

The color of the beach on Gulf State Park, AL appears to be more yellowish.  The sand is still be but not as powdery as the sand found on Siesta or Crescent beach.  The sand crystals appear to have more impurities and less transparent. 

Figure 7. Sand collected from Gulf State Park playground

Interesting sand we found in the playground of the Gulf State Park.  There are purple, green and blue particles in the sand.  Out of curiosity, we collected some sand from the play ground and looked at them under a stereo microscope.  They appears to be quartz but stained with different.  The sands seem to have more round edges caused by the weathering.  They appears to be different from the sand collected on the beach.

That's just about my general impression about the same.  Can the number tell me the same story?

The whitenss appears to be consistant with the purity of the quartz crystal found in the beach sand. I took three pictures for each collection by randomly selecting three different areas of the sand specimen.  The number of quartz crystals that are completely transparent, semi-transparent (milk white or yellowish) or none-quartz particles - nice summer project for my kids.  Megan helped out a lot for counting the crystals.

Figure 8. Counting the number of completely particles in the same specimen.  The picture shows the sand specimen collected from Gulf State Park, AL.  The completely clear quartz crystals are striked with green lines while the impurities are circled.

The beach sand collected from Siesta (1142/1149; quartz particles/all particles), Crescent (1144/1152), Henderson State Park (268/270) and Gulf State Park (446/449) beach all have over 99% of quartz.  The percentage goes down to 93% (419 / 449) for Gulf State Park if I only included completely transparent quartz crystals.  The sand from Turtle beach is completely opposite of others.  It contains only 2.5% of quartz (3/114).

Figure 9 Measure the size of particle with TSView image microscope

image acquisition and measuring software

The granunality of the sand can be measured by the size of the sand particle.  Using microscope calibration slide to obtain the conversion factor between pixels and micrometer, I can convert the size of the sand particles in the digital image from pixel to micrometer.  I sampled the particles by drawing a line diagnally and measure the length of any particles across the line.  The average size of the sands from Siesta and Crescent beach (197 and 194 um, respectively) are the smallest among all specimens.  Followed by Gulf State Park and Henderson State Park (386 and 509 um).  The tutle beach sand has the largest average crystal size among all parks (900 um).

Chucky Gal Mountain Field Trip

We have looked forward to returning to North Carolina for rock hunting since last year's visit to hiddenite gem mine.  The school was just ended couple weeks ago.  We can't miss this GMS field trip to Chucky Gal Knob.  It's a two and half hours drive from metro Atlanta.  Due to the high elevation, it was as hot as Atlanta.

Waiting at the intersection of Hwy 64 and Buck Creek

for other rock hounds to show up.

There are green rock (not showing due to the light condition) 

all-over the place.  The surface is porous caused 

by the weathering.

Ruby corundum crystals can be found in the green
Smaragdite. 

Another photos of a Ruby Corundum crystal in the 

Smaragdite.  The color of the rubies can be anywhere 

from pink to purple.  There are also some very bright green 

minerals found in the matrix but I am not sure what they are.

Picture show the layer of weathered surface and green 

interior of the smargadite.

Soap stone (Talc)

Another commonly found rock is soapstone.  They are light and form layers.  They are very soft to touch and very smooth to touch.

Some soapstone exhibit green color tone.

Some soapstones are more black in color.

Megan seems to be more interested in the stone in

white color.  In the picture is the milky quartz.

Some Smaragdite on milky quartz.

Although we have not found any ruby of good size but the sprinkles of ruby found in the green Smaragdite already making us very excited about the trip (Some member did find a strip of ruby of finger width.).  Maybe we will hit the jackpot next time.