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Posted by Rock Currier  
Rock Currier July 03, 2009 08:55AM
Click here to view Best Minerals H and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

HydroboraciteCaMg3O4(OH)3>2· 3H2O monoclinic

1.Hydroboracite & Colemanite, Boron, Californian, USA ~13cm wide

Hydroboracite is a somewhat rare borate mineral, but in some places it is part of the ore in borate deposits that is mined for industrial purposes. Good specimens of it however are not common and in fact good specimens of it are rare. Perhaps the best specimens of it have been produced at Boron, California and the Thompson Mine in Death Valley. The yellow Hydroboracite from the Inder deposit in Kazakhstan is also a strong contender, but I don't know if it got any better that the specimen shown below. Mindat currently lists 36 localities and crystals to 10 cm are known in fan like to radial spherical aggregates and in swallowtail composites.1 I have never seen any 10 cm crystals of this mineral, and think that about the largest freestanding crystals may be two or three cm.
1. Handbook of MIneralogy, Anthony, Bideaux, Bladh & Nichols, Vol V p304.

HydroboraciteGermanyThuringia, Harz Mts, Nordhausen, Niedersachswerfen, Kohnstein Quarry

Hydroboracite on gypsum FOV~ 5 cm
Hydroboracite 5.5cm wide
2.Hydroboracite, FOV 1cm

Free standing Hydroboracite crystals have been found the Kohnstein Quarry in a series of small pockets in massive Anhydrite. Other well crystallized borates, most notably world class Probertite crystals have also been found there, but of the borates found there the most abundant is Hydroboracite but good specimens are not common. The Kohnstein Quarry, Niedersachswerfen, is an anhydrite quarry mined several years for anhydrite and now inactive.

HydroboraciteIranZanjan Province, Dandy District, Gharah Gol Boron Mine

3.Hydroboracite, FOV 5.5cm

We need someone to tell us about this locality and the Hydroboracite and other minerals it produces.

HydroboraciteKazakhstanAtyrau Oblysy (Atyrau Oblast'), Atyrau (Gur'yev), Inder B deposit and salt dome

4.Hydroboracite, 6.5cm wide

I have seen only a few specimens of Hydroboracite from this locality and most of them were not the nice bright lemon yellow color shown in picture 4. Most were white and looked like the Hydroboracite from the US localities. We need someone to tell us about the Hydroboracite specimens from the Inder deposit.

HydroboraciteTurkeyMarmara Region, Balikesir Province, Bigadiç, Bigadiç Mine

5.Hydroboracite, FOV 2cm.
6.Hydroboracite, 10cm wide

7.Hydroboracite, FOV 7mm

We need someone to tell us about the Hydroboracite from the various Turkish borate deposites.

HydroboraciteUSACalifornia, Inyo Co., Death Valley, Boraxo Mine (Kern Borate; Boraxo Deposit; Boraxo No. 1 and No. 2; Clara Claim; Thompson Mine; Tenneco Mine)

8.Hydroboracite, ~20cm wide
9.Hydroboracite ~5cm wide

10.Hydroboracite FOV 1cm

Most of the good Hydroboracite specimens in collections today, especially in the USA come from the old underground Thompson mine workings before the deposit was open pitted. Most of them were collected by Jim Minette who was the Mine Manager for the big open pit mine at Boron, California. Probably the best best and largest specimens from this find is shown in picture 8 above. Wonderful big blocky Colemanite specimens were taken from this deposit when it was openpitted, but no more Hydroboracite was found.

HydroboraciteUSACalifornia, Kern Co., Kramer District, Boron, U.S. Borax Open Pit Mine

11.Hydroboracite and Colemanite ~7cm
12.Hydroboracite FOV 2mm

Two types of Hydroboracite specimens have been found at Boron. Perhaps the best specimen is shown in picture 1 at the top of the article. These are almost always associated with the typical sharp white pointed bladed Colemanite crystals that are commonly found at Boron. Probably fewer than ten good specimens have been found. The second type which is more common are tiny white micro crystals of no more than a mm that are associated with little flat bladed Tunellite crystals. We will eventually have a picture or two of this type placed here.

Click here to view Best Minerals H and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Rock Currier
Crystals not pistols.

Edited 9 time(s). Last edit at 01/22/2014 02:58AM by Rock Currier.
Rock Currier July 04, 2009 10:54AM
The first draft of the Best Minerals, Hydroboracite article has been finished.

Rock Currier
Crystals not pistols.
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