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Dirty rocks


#1

I am back from my trip to Arizona, and I did get to do a bit of rock
hounding. One afternoon we picked up small pieces of beautiful
petrified wood, and another, various bits of quartz, mostly orangy
to white druzy and chalcedony. Nothing really gemmy, but it blew me
away to just pick up this stuff off the ground, legally and for
free!

Most of the chunks with druzy are pretty well caked with dirt, and I
wonder whether anyone has a good way to get them spick and span. My
ultrasonic doesn’t seem to do it-- I suspect it needs repair, as it
makes a noise like fingernails on a blackboard.

The trip, though short, was nothing short of magical. The Grand
Canyon, Paintd Desert, Petrified forest, and a lesser-known,
spectacular formation known as Red Mountain, plus moonlight of
incredible brilliance, and the soul-soothing beauty of the
aptly-named area where my daughter was working (Alpine) have left me
feeling almost as though I had visited another planet. The towns
left me considerably less impressed, though I liked Flagstaff.

I came home on the plane with about 40 lbs of rocks…

Noel


#2

Noel

Most of the chunks with druzy are pretty well caked with dirt, and
I wonder whether anyone has a good way to get them spick and span. 

Wash with soap, water and a stiff bristled brush to remove as much
dirt as is possible, this can take as much as a week of soaking and
scrubbing.

Put mild nitric acid (the plumbers type from the hardware store is
what I use) in a plastic container with a lid try scrubbing about
once a week until you get off about as much as is possible. Some of
my stones have taken nearly 3 months. A dental pick can be handy to
get the little root fibers out and harder material.

Hope this helps.
Terry


#3

Hi Noel,

Sounds like you had a fun trip, good on ya!

The ultrasonic relies mostly on cavitation to remove unwanted
material. Cavitation relies on having a fluid in place. Cked on
material prevents the fluid from getting where you want it to go,
ergo, no cleaning or very little.

When I was digging lots of rock, something I found initially useful
was to soak the pieces in WD-40, which is vailable by the gallon at
Home Dpot or Lowe’s fro about $11/gallon or so. In a couple of days,
the penetrating qualities of the WD-40 will usually work to help
loosen up the dirt, and then a stiff bristle brush (not steel or
brass) like a scrub brush will help remove most of it.

Since you are dealing with siliceous material rather than any of the
carbonates, you might then consider a week-long soak in muriatic
acid in a covered bucket…outside and protected from children and
other small creatures. Citric acid is useful in removing rust stains
as are the commercial rust and scale removers.

Patience, elbow grease and a toothbrush will probably get you where
you’d like to be.

Good luck, sounds like fun! You never know what you’ll find under
all that stuff.

Wayne


#4
Put mild nitric acid (the plumbers type from the hardware store is
what I use) in a plastic container with a lid try scrubbing about
once a week until you get off about as much as is possible. Some of
my stones have taken nearly 3 months. A dental pick can be handy to
get the little root fibers out and harder material 

Whoa, hold on! Are you sure about the nitric acid? That is usually
not available over the counter in any strength because it is quite
dangerous stuff…and the fumes will corrode any ferrous metal
items in your shop QUICKLY. Hope fully, you meant muriatic acid, a
weak form of sulfurric acid, readily available at swimming pool
supply houses or the hardware store and often used to clean
sidewalks and other carbonate-containing materials.

The nitric will not do much to help clean the rocks, except maybe
remove iron stains, but citric acid is safer and worls better for
that.and really is a pain to handle. The muriatic will remove or
weaken the carbonates that often hold the bonded dirt together.
WD-40 or other penetrating oil is the first thing to do…

Wayne, been doing it for 50 years, but willing to learn if the new is
better


#5

Hi, Noel,

Most of the chunks with druzy are pretty well caked with dirt, and
I wonder whether anyone has a good way to get them spick and span.
My ultrasonic doesn't seem to do it-- 

Probably a good soak in hot soapy water and some work with a good
stiff brush would do the job. If not, look up someone in your local
Rockhound club who has a good water jet.

Margaret


#6

You can use muriatic acid from the hardware store, though if there
is any calcite in your rocks it will remove that too.


#7
Hope fully, you meant muriatic acid, a weak form of sulfurric acid 

I think you meant to say ‘hydrochloric acid’. Muriatic is weak
hydrochloric.

Dave


#8

Wayne – Muriatic acid is hydrochloric acid, not sulfuric acid! (And
there is nothing “weak” about either nitric or surfuric acid!)

Margaret, the chemist


#9
you meant muriatic acid, a weak form of sulfurric acid, readily
available at swimming pool 

I’m not “a corrector of minutae”. Really, I’m not. But Muriatic acid
is HCL, not H2SO4. Since we don’t want to confuse our acids…

http://www.donivanandmaggiora.com


#10

There seems to be some confusion about this. Two post stated:

Put mild nitric acid (the plumbers type from the hardware store is
what I use)..." and "you meant muriatic acid, a weak form of
sulfurric acid" 

Both are inaccurate. Drain cleaners are of three types, Sulfuric acid
(often 90% H2SO4, basically a thickened battery acid, sometimes in
the less active NaHSO4 dry salt), Sodium Hydroxide (Lye in solid
form sometimes with aluminum shreds to cause fizzes, or in solution
at 10-30%), and enzyme or bacterial cleaners. As far as I know,
Nitric acid is NEVER used in normal pluming operations. Muriatic
acid is just a technical grade of hydrochloric acid NOT sulfuric
acid. It is sometimes used to flux, clean and tin metals for
soldering, usually combined with tin chloride. Sulfuric,
Hydrochloric, Phosphoric, Sulfamic acid and Oxalic acids among
others are used to remove hard water deposits and rust stains.
Hydrochloric (Muriatic) acid is used to adjust the pH of swimming
pools (NaHSO4 seems to be the preferred acid) and clean concrete.

As I stated in a previous post, hydrochloric acid is a nasty,
volatile acid much the same, although not quite as bad as nitric
acid, causing rust in on any unprotected steel in the vicinity. I
would stay away from it unless you have a protected, ventilated
space.

Marlin, who has not taught chemistry class for 30 years.


#11

Try plain old coca cola. It’s a weak solution of oxalic acid, which
professional rocksters use to clean up quartz crystals. A lot easier
on the calcite too!

By the by, coke works great on steel tools to free up frozen pliers,
and to sharpen files. One of the properties of oxalic acid is that
it eats rust!

Jim
Mardon Jewelers
www.mardonjewelers.com


#12
By the by, coke works great on steel tools to free up frozen
pliers, and to sharpen files. One of the properties of oxalic acid
is that it eats rust! 

I bet Coca Cola works great. But it is a weak phosphoric acid
solution, not oxalic. Oxalic acid is toxic and somewhat cumulative in
its effects.

A bit of trivia- javelinas can ingest oxalic acid for several weeks
before getting ill- which is why they can dine on prickly pear
leaves as a staple, for limited periods o time.

Lee


#13

Hi

coke works great on steel tools to free up frozen pliers

My dapping block set was in the basement for a little while and now
has little rust spots on it. Can I just put the punch ends in coke to
"eat" the rust? Do they need further polishing with something after
that?

Thanks
Kim


#14
Try plain old coca cola. It's a weak solution of oxalic acid, which
professional rocksters use to clean up quartz crystals. A lot
easier on the calcite too! 

Nope, phosphoric acid and citric acid in Coke not oxalic.

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts


360-756-6550


#15
Try plain old coca cola. It's a weak solution of oxalic acid

Nope, it is phosphoric acid (H_3 PO_4) and carbonic acid (H2CO_3).
According to one source, a can of Coke has 60 milligrams of
phosphoric acid. Oxalic acid is a poison. I wonder why there are so
many misunderstandings around these common acids.

Marlin


#16

Gday;

Try plain old coca cola. It's a weak solution of oxalic acid, which
professional rocksters use to clean up quartz crystals. A lot
easier on the calcite too! 

Oxalic is poisonous when ingested So CocaCola had better not contain
that! You may be thinking of phosphoric acid which is contained in
very many commercial rust removers. It will also help build a thin
coating of ferric phosphate which inhibits further formation. For a
while. Whilst phosphoric acid can also be poisonous in large amounts
it is harmless when ingested in the amounts contained in Coca Cola.
It does like tooth enamel, though! However oxalic acid will remove
ferric oxide from mineral specimens. Just take care with it, that’s
all.

Cheers for now,
JohnB of NZ


#17

Hi Kim,

Can I just put the punch ends in coke to "eat" the rust? Do they
need further polishing with something after that? 

When a steel item rusts, the rust spots leave tiny pits where they
formed. If you want a truly smooth surface polishing is in order.

Dave


#18

Oxalic acid is a key component of a plant that is sometimes called
"mother-in-law’s tongue". If you get it in your mouth, it causes
your tongue to swell to the point where you can’t talk.

Brian Corll
Vassar Jewelers


#19

Brian

Oxalic acid is also found in black tea, spinach, swiss chard, and is
the poisonous component in rhubarb. In fact I used to make a natural
pesticide out of the green leaves of rhubarb to get rid of nasty bugs
in the garden.

Karen Bahr
Karen’s Artworx
Calgary, Alberta, Canada