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Central Texas Rockhounding

Posted by Rachel  
Rachel
Central Texas Rockhounding
February 09, 2007 04:26PM
Hi there, I'm an amateur rockhound looking for some good places to hunt for interesting minerals in the central Texas area. I read on here about some garnets in Llano county, is there any non-private land I can go collecting on?

Also, someone posted on another thread about strontianite on Mt. Bonnell. How would I go about finding that? I've been to Mt. Bonnell severals times, so that'd be a good place to start hunting.

Can anyone help me?

Unfortunately, I can't meet up with anyone since my dad is over-protective.. So I'll need either directions or a good description of the area please :)
Rachel
Re: Central Texas Rockhounding
February 09, 2007 04:29PM
Oh yes, and what is a pegmatite? I've seen that word used on here several times.
Re: Central Texas Rockhounding
February 09, 2007 05:14PM
Hi Rachel

Perhaps if you did some research on mineral clubs down your way you could ask your father to take you to meetings and on field trips? Joining a club is the best way to find out where the good collecting spots are - since the club will probably hold trips to them, or members will be planning trips and inviting other members to go. And so long as your father accompanies you, there's no worry about meeting the "wrong sort of person." (BTW: He is absolutely right to be protective when it comes to meeting people you don't know, and there is no way you can really get to know people on-line - all you learn about them is what they want you to learn. Predators are often very good at comming across like good people - which they most certainly aren't... - I'll stop preachin' at ya now! :~} )

There is a web site called "Bob's Rock Shop", the URL is "rockhounds.com", where there is a link to a list of mineral clubs across the country in the American Federation of Mineralogical Societies. Scroll down the Table of Contents page at Bob's until you find it, then click in to the list. There are several clubs in your general area - maybe one of them close enough for you and your father to join. (A good friend of mine is a member of the big club in the Houston area, and if you are anywhere near there she would be a great person for you to meet - as would the rest of that gang. It is a highly repsected, very active, club.)

As to your question about pegmatite, it is basically a very coarse type of granite that forms very late in the development of granitic igneous rock bodies and ends up carrying all the highly volitle components that remain in flux until the very end of the crystallization process. These volitiles form a bunch of neat late-stage crystalline minerals that interest collectors - things such as Tourmaline Group species, topaz, beryl (including the aquamarine variety), Apatite Group species, spodumene, and others. Collectors flock to pegmatites to collect the way birds flock to bird feeders in the dead of winter to eat... :~}

Regards

Alan Plante
avatar Re: Central Texas Rockhounding
February 09, 2007 06:14PM
Hello, Rachel.

The Austin Geological Society is sponsoring a field trip to south Texas
next weekend, Feb. 17th. Field collecting at several uranium mines will be
done, and visiting the sites of the old mills is planned. A chartered bus will
make the trip, and a field guide and CD will be provided. You can see photos of
a preliminary trip to the location in the collecting forum.

The Austin Gem and Mineral Society meets the fourth Thursday of each month. We try
to have one field trip a month. www.austingemandmineral.org has a map to our
clubhouse and some information. The website is undergoing a complete makeover,
but the basic information is still there.

If you like, I can email the latest AGMS newsletter.

Paul Bordovsky
Austin, TX
Rachel
Re: Central Texas Rockhounding
February 09, 2007 06:38PM
Thank you for all of the information, Alan! I'll take a look at that site and see if there's any clubs I can join :)

Thank you Paul, I will definately have to take a look at that site! That really sounds like an interesting trip.

Another question about pegmatite -- is it out in the open, or do you have to dig for it or break stone open?
Re: Central Texas Rockhounding
February 10, 2007 04:27AM
Hi Rachel

Pegmatite typically forms as dikes or sills in fractures or along planes in bedrock deep beneath the surface. Erosion and uplift bring them to the surface, where they become exposed, found, and mined for a variety of minerals (including gem stock and specimens of crystals.) Rockhounds basically visit the mines and pick through the tailing piles - or "mine dumps" - in search of specimens. Or, in some cases, they might work an unmined outcrop that has been exposed - or work the faces of old, abandoned, open pit mines.

Any type of rock that is "mineral rich" (from a colletor's perspective) might be visited by collectors in search of specimens, whether the rock has been mined or not. It's just that when mining has broken up the rock into more managable sized chunks it is easier for collectors to get specimens out of them: "Ledge work" is generally pretty tough to tackle.

"Loose deposits" (stuff that has been eroded out of the bedrock and deposited in one way or another) are also worked by collectors; such as screening gravels that contain certain minerals, or working scree piles at the bottoms of ledges. Panning for gold falls into this category of collecting.

KOR!

Alan
Re: Central Texas Rockhounding
February 12, 2007 10:40PM
    
Hi Rachel,

If you want to see some of the pegmatites in the Llano and Burnet County area, I'm usually out there every weekend collecting. I make the one hour drive to my collecting sites from home in southwest Austin.

To answer one of your questions, no, as far as I know all of the collecting sites in central Texas, including the pegmatites, are on private property and not open to casual collecting. About half of the effort I put into collecting from these sites is spent dealing with ranchers and landowners in order to secure permission to collect. In some cases, my access is on a lease basis.

If you would like to visit one or two of these pegmatites and collect some great specimens, have your father call my cell phone at (512) 848-8309. He can also reach me at KLRU-TV in Austin, where I'm the transmitter engineer. If you prefer, you can send me a private message on this site and tell me how to contact your dad. You mentioned visiting Mt. Bonnell several times, so I assume you live in Austin. If that's the case, you and your dad can meet me in Burnet, or we can caravan from Austin.

Frank

P.S. Your dad isn't being over-protective, he's just doing what dads are supposed to do. Look it up, it's in his job description.
avatar Re: Central Texas Rockhounding
February 13, 2007 12:52AM
    
Hi Franklin! I hear you collected with David Aldridge at Llano! I talk to him a lot and he has taught me about Texas mineralogy and I have done the same with CT mineralogy. I was told that you guys found a HUGE mass of purple Fluorite at the mine (I heard around 10 feet with multiple pockets of large crystals) along with the radioactives which the area is known for. I also heard about your Monazite find from him! I think he's done a good job convincing me to go on a rockhounding trip out to Texas. I just don't know when that's going to be. Mount Bonnell has some nice stuff- Beautiful Stronianite! None of that here in Connecticut! Well, as far as I have seen.
Re: Central Texas Rockhounding
February 13, 2007 07:20AM
    
Hi Jeremy,

Yes, I invited David and his dad to collect from a couple of my more "showy" pegmatites, Badu Hill and Petrick. Although they're only four miles apart, their mineralogy couldn't be more different. Badu Hill is a predominantly late-stage hydrothermally altered pegmatite while Petrick is more magmatic. Petrick is only a little over a mile south of the now inundated site of Baringer Hill, the most fabulous of them all.

Because the Badu Hill Pegmatite was highly altered by mineral-laden superheated water after it formed, the variety of minerals found there is just amazing. You can pick up a 1kg chunk of REM conglomerate there and identify up to 25-30 different minerals in it. It's not unusual to find fluorite, pyrite, chalcopyrite, titanite, hematite, magnetite, bornite, covellite, gadolinite, fergusonite, anatase, uraninite and about a dozen others, including gold and silver, in the same radioactive specimen. I'll try to post some site photos in my gallery within the next few days.

There is one sad note to report however, the current owner of the Badu Hill Pegmatite has informed me that he intends to fill in the excavation at Badu Hill. So far, there has been no date announced, but he did say that if I wanted to get anything from the pit that I ought to do it as soon as I can. I've offered to buy the 10 acres that encompass the pegmatite, but he refused to sell at any price. I think he intends to offer the entire 120+ acre site for sale to developers and the presence of a quarry on the property would sour the deal.

I wish that I could impress upon him just how unique and special a place he owns, but so far, he's not having any of it. I suppose I shouldn't complain though. He has granted me exclusive unrestricted access to the property since he bought the place a couple of years ago and refused to accept payment for it. I just hate to see the place become somebody's strip shopping center. As you can see, if you plan on accepting my invitation to do a little Texas peggin', you'd better think about doing it sooner than later.

Frank

Frank
Scott and Angela Crumley
Re: Central Texas Rockhounding
February 19, 2007 10:18PM
Rachel, actually, you can find all kinds of neat minerals, crystals, and rocks just by taking the back roads and collecting right along the roadway. You should talk your Dad into taking you for a nice country drive out in the area of Llano, Mason, and around the Llano Uplift. Go purchase a book called "Roads of Texas" which has all the county roads that are paved and unpaved. We do most of our collecting using this map book, looking in mineral rich areas. Just recently we came upon a wonderful area rich in Serpentinite in Gillespie county, just south of Llano, near Willow City. The views were spectacular and th rock collecting was fun. We have found veins of Selenite that are yards wide and tens of feet long in Lampasas county along the county roads. We have found smokey quartz, topaz, calcite, pegmatite, rose quartz, some wonderful flourescing chalcedony type calcite. One nice drive is to Mason, then out towards Fredericksburg and take the James River road down to the James River and then around to the Llano river. At both rivers you will find a nice selection of different rocks and minerals. I hope you have a vehicle which will travel over dirt roads. Remember, if you are on a country road through a ranch, you may have to get out and open and close gates. Just be sure to keep to the county road and keep gates closed behind you. Most ranchers do not mind people traveling through with an occasional stop if you do not disturb the livestock or take hikes out onto their land. Collect along the road and you will find all kinds of stuff. Lampasas county is wonderful for fossils both in the Limestone roadcuts and in the riverbed of the Colorado River. Have fun! Oh and by the way, if you find that wonderful sky blue selenite at Mt. Bonnel, tell me where it is...I sure want some.
Re: Central Texas Rockhounding
February 20, 2007 04:17AM
    
Actually I think the sky-blue selenite at Mt. Bonnell is probably underneath somebody's swimming pool by now. When I first moved to Austin about 23 years ago, you could drive up to Mt. Bonnel and wander all over the place collecting to your heart's content. For about the last 15 years or so, Mt. Bonnell property has been bought by developers who have built million-dollar mansions all over the place. There is a city park at the pinnacle of Mt. Bonnell that overlooks the Colorado River and you could wander the trails there right up to the edge of the cliffs. Since the riverfront property beneath the Mt. Bonnell overlook has also been covered over with mansions, wandering off the trails at the park has been forbidden. It seems that the rich folks living underneath the overlook park began complaining about litter and falling rocks from above. The other source of selenite and strontianite in Austin, the Convict Hill Quarry, is now occupied by new homes and a strip shopping center.

Frank
Re: Central Texas Rockhounding
February 27, 2007 11:54PM
Hey, Kids!

Are you sure it was sky blue selenite? I've seen blue celestine (aka celestite) from Austin, pretty nice crystals with darker blue terminations.

Speaking of Central Texas, I'm thinking of moving south and/or west to find a full-time teaching job after 3 years of subbing in Michigan. College Station is a possibility, although I'm also considering New Mexico, North Carolina and northern Florida. I got all discouraged about Texas when I realized it's over 500 miles from College Station to the Big Bend agate diggings. If I want to drive that far up here, I can go from Ann Arbor to the Keweenaw Peninsula! Is there hope for mineral collecting in Aggie country?

Bill
avatar Re: Central Texas Rockhounding
February 28, 2007 12:00AM
    
If you are interested in mineral collecting around College Station, Arkansas is fairly close (at least as far as drivers in Texas are concerned). There are a number of areas for petrified wood in east Texas.
Chris Kaufman
Re: Central Texas Rockhounding
March 15, 2007 01:26AM
David Von Bargen Wrote:
-------------------------------------------------------
> If you are interested in mineral collecting around
> College Station, Arkansas is fairly close (at
> least as far as drivers in Texas are concerned).
> There are a number of areas for petrified wood in
> east Texas.


Hi David,

My wife and I have the opportunity to be in Austin this coming week and we love to rockhound (especially with the kids) every chance we get. I did some snooping on the net and found some threads that said Turkey Creek and Whites Creek in College Station are prime areas to find petrified wood. True? Are there any specific areas along the creeks that are best? What else could we find between Austin and College Station? Any tips/details would be very much appreciated. Thanks

Chris
Re: Central Texas Rockhounding
March 18, 2007 12:48AM
    
WOW - Now this is helpful but I'd sure like to connect with a field collector while I'm visiting in Georgetown for the next 3 weeks. I've been out looking and finding interesting chert on Cty road 112 south of Llano. However I'm a very serious calcite, quartz, and fluorite crystal collector and would love to add several Central Texas specimens of each to my collection. Can anyone help!

Bill Morgenstern from Fort Frances, Ontario - CANADA
Re: Central Texas Rockhounding
March 18, 2007 11:27PM
    
....however I'm a very serious calcite, quartz, and fluorite crystal collector and would love to add several Central Texas specimens of each to my collection. Can anyone help!


Has a cat got climbing gear? Reply sent via PM.

Frank
Re: Central Texas Rockhounding
March 19, 2007 01:22AM
Mr. Bonnell is blue CELESTITE some with Strontianite balls growing on them. Unfortunately most has been taken by development for many years. In 1976 i was offered some quartz from Mt. Bonnell by a college student. I told I did not think it would be quartz, however, would like to see it. He proceeded to open the trunk of his car, lift out and approximately 30 pound bag of Blue Celestite which he dumped from about 4 feet onto a concrete parking lot. Cleavage fragments flew every direction. Through tear stained eyes I was available find 3 (2"-3") that went into my personal collections. In recent years ''ve only found small pockets on the park road leading to top of the hill with xls. that have faded to white. I now live 1200 miles away. Mt. Bonnell is basically history for the average collector.

Other Celestite locales are Convict Hill just West of Austin, and several locales on Bull Creek, and highway 1&183 interchange. Be advised that collecting any minerals in Austin are now covered by a City Ordinance that forbids it and is considering a felony "Stealing City Property". I know of at least one case of a person collecting on private property with permission that was arrested and charged with stealing city property. Highway 1&183 was a great locale for a few months until and individual that I had warned 3 days earlier was badly injured by a several ton boulder requiring city rescue team to get him out. Very dangerous blast zone, in which I as and experienced collector was extremly cautious/nervous with overhangs. People would bring small children out and let them crawl around on the ledges. As a geologist i was able to get the construction foreman to take me on the site later, however , most of the Celestite areas were quickly covered. It produced and abundance of blue to with xls. many with associated golden calcite. (someday I will be able to post some pictures). Most were coated with a powdery white residue (strontium?), and many were partially resorbed/etched and many had small clusters of cream colored strontianite on them. I have lots of this stuff just as locale pieces since it is now permanently covered by concrete/steel and grass, plus heavy high speed traffic.
More on Bull Creek and Convict Hill in next messages I need to sign off for now. Every new roadcut in NW and E travis county is a potential bonanza. ......Harold Hal) Prior
Re: Central Texas Rockhounding
March 19, 2007 01:39AM
Convict Hill is and old quarry that was converted into a shopping mall some years ago. It produced celestite, Calcite, and Strontianite. The celestite I collected was mostly small pale blue xl. clusters. The real prizes were the Strontianite pockets with strontianite pseudos of Calcite and/or celestite. I collected several cabinet size pseudo pieces many years ago plus have many small thumbnail sized that pieces that range from locality pieces to decent tn's. About 15 years ago I stopped at the high wall to the west of mall after a heavy rain and saw something blue up about 12 feet perched on a ledge in the mud. With my extended fly rod and my 6' plus height was able to nudge each off and catch it as it fell. They were two fabulous celestite cluster (3"-4") with ble and white, barrel shaped xls. much like the Lime City, Ohio celestites. I've never seen anything similar from the area. Obviously it was washed down from many feet above during the storm. My last visit there you could find small pockets of Strontianite in the wall of alley behind the mall. Warning - The dumpster behind the Chineses restaurant will definitely take your breath away on a hot summer day! Bull Creek locales next! .....Hal Prior
Re: Central Texas Rockhounding
March 19, 2007 01:48AM
More Austin I have acquired: Pyritized Oysters SW Austin, great sea urchins and other cretaceous fossils west side, small blue barite rosettes south Austin (The experts say no barite in Austin - they were wrong!), Bee Cave Road, fantastic snow white quartz floater clusters in soil, up to 4" (on 3M high security property is locale I was given by a security guard that collected them). Nice small twinned calcites in pockets, NW loop 360. I love the whole area for collecting potential! .....Hal Prior
Re: Central Texas Rockhounding
March 19, 2007 12:47PM
More Austin info - Bull Creek. I know of 4 locations on Bull Creek. First is just inside the loop 360 in NW Austin. Pockets in the stream bed produce small clusters of celestite in elongated gray to white xl. clusters. Next just outside the loop on south side of road Nice pointed xls. and flat terminated xl. ranging from gray to clear with dark blue terminations. Further west on North side of the road are similar occurrences about 8-10 feet up in really hard material and down in the stream level a soft sandstone layer. This soft layer can be worked with a screwdriver easily until you find a pocket which can produce some superb gemmy with dark blue terminations xls. The best I seen was a 3" waterclear, double terminated xl. with deep dark blue terminations that was found as floater with no attach points. Was found by a young girl wading in the creek. I offered $100 for it and was refused, unfortunately that was all the money I had with me. It was clearly museum piece! Further to the west at a small city park you can find in a small clay seam you can find small (1-2 cm.) light blue DT celestite xls. Caution - All of these sites are in the now forbid collecting zone. Further to the West isolate pockets of celestite can be found which are porbably outside the city of Austin, but you need to check owner status. ......Hal Prior
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