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Mason Tx - Topaz specific question on streambeds -Commanche creek

Posted by Lance Kirkbride  
Mason Tx - Topaz specific question on streambeds -Commanche creek
April 09, 2008 07:22PM
We have gone and stayed a few times at the Lindsey Ranch out in mason and are going back for several days towards the end of may.

I have a question or two on the topaz that can be found there, if there is anyone that is familar enough to be able to asnwer the question, as the ranchowner was unsure herself.

On commanche creek, where we primarily worked the stream beds for topaz there are several spots of "schiz(spelling?)where the creekbed cuts thru them. Now we primarily worked the stream beds by digging down and sifting thru the gravel etc on the screened racks I had built, but I was wondering...is it worth prosepcting the actual rock faces of the stream beds themselves and even looking at the rocks that are not up in the streambed but rather up on the cliffs and the small 1700 foot mountain that one crosses to get to the creek?

( I guess in other words...can the topaz actually "form" right there or does it only from upstream and come down form the katamecy rocks and deposit itself in the streambeds?)


Hope this question makes sense. I am wanting to know if we should concentrate our efforts in the commanche creek stream beds or if there is a better spot to work in and around the streambeds.


Thanks for any and all replies


( I do have all the tools needed to split the rock faces of the "schiz" where the stream cuts thru it..just a bit uncertain as to what to look for...)
avatar Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 09, 2008 07:29PM
    
It's probably schist. The topaz there is from the pegmatites (the coarser granites) and wouldn't be found in the schists itself (you might have pegmatites cutting through the schists though).
Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 09, 2008 10:35PM
Without making myself sound 'too naive" ( and yes schist it is I believe), is there a way to determine if one is actually looking at a pegmatite structure? ( any websites that show pics or anyone familar with the mason texas area to be able to answer

thanks
I am certainly no expert on Texas topaz or Texas topaz localities around Mason. But, I have been to Mason and have a geology graduate degree from UT Austin. The best of my recollection is that all Texas topaz in the Mason area was alluvial and that the actual pegmatites were eroded away long ago. The topaz crystals were found around 100 years ago by ranchers in stream/river gravels. There are probably several geology professors here in Texas, that could give you the answers you need. One is retired here in the Dallas area, but is still quite active.
avatar Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 09, 2008 11:15PM
    
The grain size of the pegmatite is much larger than the surrounding rocks (1" to 20+feet). If the schist is biotite or amphibole rich, it will be black or very dark in color. Granitic pegmatites will be white to tannish pink in color. Most of the material is alluvial (streams), but occassionally it has been found in pegmatites.

[www.yourgemologist.com]
[en.wikipedia.org]



Edited 1 time(s). Last edit at 04/09/2008 11:20PM by David Von Bargen.
[www.pegmatology.com]
[pegmatopia.ou.edu]
[www.minsocam.org/msa/special/Pig]
Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 10, 2008 01:58PM
Thanks for the replys, sounds like then its all going to be in the stream beds from what you are saying.

So thats where we should concentrate then, rather then looking for a structure to actually " chip away at"
avatar Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 11, 2008 03:25AM
Hi!

I have prospected for topaz at the Seaquist Ranch in Mason County. The ranch is a huge area of crumbling pink granite hills and with some vugs. Large topaz have been found on the hills in the stream and by breaking into vugs. You can get a key to the gate and pay a small fee (double check my directions plz) at the gas station in Mason it was about 8 years ago I went hopefully the location is still open. Nice camping areas and very scenic place real "Hill Country" TX! Here are some directions: From Mason go NW on US 87/Rt 377 5 miles to jct w/ Rt 29 (picnic/wayside area here) then go west on Rt 377 for .6 (6/10) miles there is a locked gate and a dirt trail that goes North. Drive down towards the creek. There are a few places where old vugs were opened if you look hard up the creek (long hike) along some rock ledges. I managed to dig some quartz crystals, nicely formed smokeys but the topaz remain for you to find. I had a book showing a lucky digger back in the 1950s cleaning out a large vug along the stream at the location and amazingly I found the exact spot! I wondered around the ranch for 5 days looking for gems in the warm spring sunshine, it will always be a happy memory. Good Luck Digging!

JT

Thank you William for the correction.



Edited 3 time(s). Last edit at 04/18/2008 01:28AM by John Truax.
Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 11, 2008 12:29PM
Thanks for the reply John. Yes Ive heard of that ranch...we have been to the Lindsey ranch and will be going again at end of may for several days. I am still trying to do as much research as we can to find the best spot(s) out there to hunt...don't know if it would be worth taking the time to go to that ranch for part of a day while we are out there or just concentrate on the lindsey ranch ( which is on Commanche creek)

Personally while I have all the equipment for sifting and digging etc..Id love to be able to try and find a pegamatite structure and find a quartz vug ( not sure if my terminology is correct) and do some direct "chipping"...just not sure if thats possible or which ranch is the best.

Anyone have personal exp on the lindsey ranch by chance?
avatar Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 11, 2008 04:18PM
    
Lance:
The actual origin of the topaz (and smoky quartz) is from miarolitic cavities in the granite, and while these resemble pegmatites, they are decidedly different. Pegmatites are distinct bodies of coarse granite that are injected into fractures or openings in the granite itself (interior pegmatites) or into rockes surrounding a granite intrusive mass (exterior pegmatites). Exterior pegmatites are found in many rock types, typically schists and gneisses, and are often large and complex (ex: southern California tourmaline pegmatites; Black Hills, South Dakota; Spruce Pine district, North Carolina; Maine tourmaline/apatite pegmatites). Interior pegmatites are usually much smaller and do not have the complex mineralogy of their exterior cousins, generally containing quartz, feldspar, mica, and minor accessory minerals such as epidote, schorl tourmaline, topaz.

If you can find a copy of John Sinkankas' "Prospecting For Gemstones and Minerals", there is a great picture of an excavated miarolitic cavity in the area you are interested in. It is clearly not a pegmatite but an abrupt opening in what is otherwise solid granite, showing the fractured nature of the rock surrounding these openings. A true miarolitic cavity is basically a gas and/or liquid trapped in the granitic melt, part of the rock that does not solidify or crystallize. The minerals that compose the granite itself then crystallizes directly into the opening, in their characteristic idiomorphic faces, and uninterrupted by adjacent minerals (euhedrally). Late minerals, associated with aqueous mineralization, especially topaz, grow into these "pockets" provided the right conditions are met (chemistry, temperature, pH, pressure, etc.)

Subsequent weathering conditions often expose and wash these minerals into the soil horizon, and eventually into the nearby stream drainages. Since most of these minerals are durable, hard, and chemically-resistant, they end up in alluvial accumulations in the stream bed. This is what you are finding by washing through the gravels.

But if you want to find pockets, you need to hunt the granite host rock itself; sometimes crystals will be freed by weathering and are found downslope from their vug origins, in which case, you may be able to trace this material to its source. Typically, miarolitic cavities do no exhibit coarse, pegmatitic rock except for immediately adjacent to the vug opening, but in some cases, streaks or schlieren of coarse granite may lead you to a hidden pocket. Sometimes grass or other plants take root in cavities, and they are found by observing where plants grow from what is otherwise solid rock; removing the plant matter will allow access to the pocket contents. The material from a pocket will be in much better condition than what you find in the straem gravels, where weathering wears down crystal faces and edges, sometimes to the point of smoothing them out alltogether. Crystals extracted from vugs or cavities tend to be in fine condition, with sharp faces and shiny surfaces (except for duller crystals like microcline!)

The miarolitic cavities of Mason County, Texas are much like the cavities found in the Sawtooth Mountains and Crags Batholith of central Idaho; also like those found in the Tarryall Mountains of Colorado.

I should add here that in some cases, the pegmatitic streaks or schlieren that surround some miarolitic cavities are basically "micropegmatites" and there is no fine dividing line between them and true pegmatites, but since most miarolititc cavities are pretty limited in overall size, they just don't qualify as a "true" pegmatite. There is some crossover between them, so don't give up alltogether searching for pegmatites in a miarolitic granite!
Chris
Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 11, 2008 08:13PM
William, Thank you for your detailed reply!

A question or two, and bear with me as our family is very new at this.

Using the example I am familar with On the Lindsey ranch commanche creek flow thru the ranch...at several spots the stream beds cuts thru "shist" I believe...but I do see some spots where I can see some quartz like veins and in spots the creekbed is full of large rocks/small boulders...some have quartz type veins in them.

Since we will be out there for a more extended period of time toward end of may I will be spending much time rockhounding...and was wondering is there a way I can tell by looking at the "shist" face is it just "rock" or it is possible there could be vugs containing crystals?

The ranch owner herslef was not sure...and the Lindsey ranch is in the same basic area as the Seaquist and the (Hoffman)? ranch...basicly all around the area just north of mason.and west a td of hwy 87


I guess my ultimate question I wonder is how do I as a lay person tell if there is a chance im looking at potential "vug crystal" containing rock lol...I will search for the book u speak of and we may go over to the seaquist ranch for an afternoon since we will be so close at end of may to see what the difference is
Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 11, 2008 08:50PM
BTW William,

I just have placed an order for a 1970's copy of the book! via amazon (Prospecting For Gemstones and Minerals) fomr the author you mentioned...it has gotten great review. They had a slightly different titled one listed that was about 3 times as much which is a 1995 edition but the reviews say they are all good ( not sure why the 1995 one is 100 pages more but most seem to refer to the 1970's one)

Thanks!
Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 11, 2008 09:09PM
well..I actually decided to cx the order for the 2nd edition and re-did the order for the last one from 1995...figured may as wellhave the most up to date and it says its about another 75 pages long..slightly different title

Field Collecting Gemstones and Minerals by Sinkankas, John

again...gotten very good review..so IM looking forward to getting this book

thanks again william...
avatar Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 12, 2008 03:17PM
    
Lance:
Sinkankas' book had two different titles, depending upon the publication of the specific edition; each is a little different (I have both).

As for looking in the schist, this will probably not yield good results, but you never know about these things....there are no hard and fast rules about geology & mineral collecting in general. Minerals are where you find them. However, miarolitic cavities, by definition, occur only in granitic rocks. What I know of the area you are hunting in, the cavities are found in granite. This doesn't mean there are no pockets in the quartz veins cutting through the schist. You should spend at least some time examining these for signs of pocket mineralization.

If I was there, I would be hunting in the granite. Look for "float" or crystals/fragments weathering out of the pockets. Material will gradually slide downhill with the soil, exposing (sometimes) the loosened pocket debris. It can often then be traced to its source.
Chris
Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 12, 2008 03:36PM
Thanks Chris...Ive seen on the ranch also...especially on the little 1700 foot mountain you go over to get to commanche creek spots in the ground on th eslop and top where you see quartz or a hunk of rock sticking out with quarts in it ...I was thinking it may be a good idea to try and chip away at some of these thru the dirt to see if anything there?

Thoughts?

(I "think" I can tell the difference and know granite when I see it...but we are very new at this ..its one of those things I wish I had someone to one time say " ya see that thast granite there...see this ..this is "garbage rock" etc lol)
avatar Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 12, 2008 03:45PM
    
[uts.cc.utexas.edu]

[www.lgsweb.org]



Edited 1 time(s). Last edit at 04/12/2008 03:53PM by David Von Bargen.
Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 12, 2008 04:22PM
David,...

hey thanks! I am at work today and am going over these now....this is great.

Thank you for taking the time to make a reply sir!
Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 12, 2008 04:27PM
Now the real question...

anyone here familar with the Lindsey RancH or if not....the Seaquist one?

And if so...could you give some basic "ranch specific" directions ( or if by some miracle you have GPS coord as I do have a garmin mapping handheld gps unit))

some gps coord as to some locales on the ranch(s) of some "vugs"? ( would LOVE it if someone was familr with the Lindsey ranch and could offer advice as that is where we will be staying again at mays end..but we will probably go over for at least 1/2 a day to the seaquist ranch)

While we have been to the lindsey ranch...it was only for one night so we lots of ground yet to "cover"

thanks all...you are keeping me busy today researching
Hi Lance,

I have been out to the Seaquist Ranch a few times, but I am very much a rookie rockhound and haven't found anything more than some very impressive quartz. It's a great place to hunt - the opportunities are virtually endless - and my fiance and I learn a little more about the landscape and find a new place to cover each time we go. We're going to find some topaz there, darn it!

We've had the most luck finding cool stuff in the stream beds. We try to look for an area that has a lot of large rocks that people probably haven't moved before, and we move them and dig under them. I would also bet that with all the recent bad weather, there has been a lot of erosion along the sides of the streams that has released some of the deposited material, so there is really no place better than the other to dig.

You don't really need directions to the Seaquist Ranch the first time you go. You can call Mr. or Mrs. Seaquist and arrange the day you want to go (325-347-5413), then you call Mr. Seaquist when you get to Mason and he will meet you at the Town & Country Store and let you follow him out there. It's a lot of fun. If you go, head right when you get down to Honey Creek, and follow the stream beds that direction. You can hike up a long way & that seems to be the lesser beaten path and the most opportunity.

Hope this advice helps. But then again, I haven't found anything of value so my opinion might not mean jack! :) Good luck!!!
Re: Mason Tx - Topaz specific question on streambeds -Commanche creek
April 30, 2008 06:41PM
thanks for the reply...we are going to be out there the week of memorial day...and plan to go over to the seaquist ranch one day to see how it differs from the lindsey ranch.

id still like to find some "vugs" of some kind, we are well equipped though for stream hunting...I have screens etc Ive built and we tested them the day we were out in march and they worked well...we just didnt have much time as we only stayed one night...this time we will be there almost a week
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