No. But blue agate is known from Namibia, blue pegmatite quartz from Brazil and blue quartz in some Scandinavian igneous rocks. Generally, the colour is attributed to different types of microinclusions

‘Blue quartz’ is according to mindat.org (quote):

“An opaque to translucent, blue variety of quartz, owing its colour to inclusions, commonly of fibrous magnesioriebeckite or crocidolite, or of tourmaline. The color may be caused by the color of the included minerals or by Rayleigh scattering of light at microscopic inclusions. The term is sometimes also used for massive quartzite with inclusions of blue minerals.”

Blue chalcedony is a blue variety of extremely fine-grained (cryptocrystalline) quartz.

Here is a selection of blue quartz (chalcedony) localities given in mindat.org:

Altura, Spain

Antequera, Spain

Wilmington, Vermont, USA

Cornog, Pennsylvania, USA

Rio delle Ossa, San Clemente, Italy

Woburn, Massachusetts

Planet Mine, Arizona, USA

Qinglong Mine, Qinglong, China

Ysterputz Mine, Karas Region, Namibia

Best regards,

Günter Grundmann

Dear Guenter and Axel, many thanks for your nice explanations! Best wishes Daniel

Dear Daniel,

In my first answer, I have not yet accurately mentioned the blue quartz occurrence in epithermal gold deposits. I am sure that in many epithermal gold veins blue quartz exists, even in microscopic dimensions. I have seen specimens with blue quartz in samples from (for example)

Banská Bystrica, Slovakia

Maramures, Romania Goldfield, Nevada, USA Guanajuato, Mexico San Juan County, Colorado

Best regards,

Guenter

Dear Gunther, many thanks for your detailed answer! That is really nice. Best wishes from Daniel

Hello Daniel. Several of the intermediate to low sulphidation epithermal deposits in the silver trend of north-central Mexico have bluish quartz banding. Also, as one of the later stages of veining, you can find amethyst purple quartz. Secondary hues of blue and red can be found in the amethyst. The color of amethyst has been demonstrated to result from substitution by irradiation of minute amounts of trivalent iron (Fe3+) for silicon in the structure. Cheers... Ben

Hi Ben, many thanks for your nice reply! Best regards Daniel

Maybe the blue color is due to Sr that have been remobilized due to acid fluids from epithermal environments

Judging by the photo the bluish band is moss texture chalcedony in the classification of Dong et al 1995. Moss texture is due to microcrystalline to fibrous quartz replacing the radiating microlites in spherical chalcedony. The chalcedony originates from silica gel and the quartz from expulsion of H2O from the gel during low temperature healing and crystallisation. In our experience the blue color is internal reflections in the low temperature crystalline quartz with sparse Fe sulfides (usually marcasite) and quartz lattice Fe2+ derived from breakdown of the marcasite. Jim Saunders and Jeff Mauk have described similar things in thin section and SEM.

The attached picture of blue lace agate from the geology wonders page has the explanation here. It is a bit hard to tell from your picture if it is truly blue as in the gem quality material.

A member of the chalcedony family, blue lace agate is yet another type of gemstone that features microcrystalline quartz in its composition.

The enticing blue hues of the blue lace agate stone is due to the mix of copper salts present in the mix. With a density of 2.65 and a hardness of 7, this surprising member of the banded chalcedony family is as easy to find as other agates.

Namibia – the African country where the gemstone was rediscovered and classified in 1967 – has some of the largest blue lace agate exploitation areas. Although it looks like a delicate and soft gemstone, blue lace agate is quite hard. Its sturdiness makes it a perfect gemstone for exquisite pieces of blue lace agate jewelry.

Hi Gregg, many thanks for the nice photo and your detailed explanations!

In the Proterozoic orogenic gold deposit "Barsele", located in northern Sweden, the blue quartz is associated with the higher temperature phase veins. These show markedly higher titanium and aluminum content in the quartz. Titanium in this phase of quartz averaged 110 +/- 33 ppm, whereas all later phases of quartz veining contained less than detection of 16 ppm Ti. Titanium-geothermometry yielded a 625 +/- 75 deg C. Temperatures of