Dudley,That's consistent with my observations--the best of the Brazilian Paraibas are  unique.   I've seen a fair amount of the material from Mozambique and Afghanistan.  I've seen some material listed from Nigeria on line, but not in person.  None of it came close to the ...

Those specimens resemble some of the matrix specimens I've seen on sale in Teofilo Otoni from dealers I trust who have connections with the mines in Paraiba.  The matrix is consistent with the specimens I've seen from Batalha.  While it is true that I have not seen the most classic ...

So, after 4 collecting trips to Sri Lanka and examining a whole lot of sapphires, I cannot say I have ever heard of that site.  That is not particularly surprising, as there are mines all over the island, and unless they are yielding lots of gem quality material, they won't be all that well ...

Dioptase is a tough one.  I noticed a while ago that Joel Arem didn't include dioptase among the plates in his Color Encyclopedia of Gemstones.  Joel was working with film, so clearly it's more than just a matter of sensor sensitivity (it may have also been the fact that there are so few ...

Hi Jorge,Sorry for the delay in responding.  The spreadsheet includes the mineral species, variety (e.g Beryl, var. emerald), origin (to extent known), where obtained, price paid, dimensions, cut type/shape/quality, treatments if any, analyses performed (if any), color(s), phenomena the stone ...

I've seen a lot of friable mica-schist like this.  Graves Mountain is full of the stuff, and many of the Himalayan Mountains have vast areas of it--a real problem for climbers.

My gemstones are about the only part of my collection that is organized.  I have most of them in 1-inch gem jars with small labels placed under the foam showing through the bottom of the jar.  A number on the label indicates the entry number in a spreadsheet with more detailed info.  ...

I agree that Congo is probably the origin.  They produce an astounding amount of high-quality malachite there and have for decades.  When I was in the Peace Corps, markets all over the continent featured carvings of Congolese (then Zairian) malachite.  I've even seen it in Madagascar.

Some of the larger cumengeites, 8 mm largest dimension.

Large parcel of small stones from the Boleo District showing the progression of epitaxial deposition from boleoite to cumengeite.

Kristen,LED lighting is rarely a single wavelength.  Usually, the LED itself is a wide-bandgap semiconductor, such as Gallium-Nitride, which emits in the blue to violet (and perhaps into the Ultraviolet).  However, the plastic surrounding the LED is doped with phosphors that fluoresce in ...

OK, sorry I didn't see this earlier.  The thing is that in a crystal, there is already substantial overlap of orbitals--to the point where it makes more sense to look at the crystal as having energy "bands" in which the charge carriers exist.  Charges in these bands may be localized ...

Albite and maybe siderite?

Thierry,I was in Antsirabe a bit over a month ago and saw no samples resembling this in the Cercle Mess mineral market.  Do you have photos from the 2004 find for comparison.  I couldn't find anything similar online.  Cercle Mess tends to sell more aesthetic specimens, but there ...

Kristine,Virginia is a big state with highly variable geology.  The central/southern portion has some quite nice pegmatites that produce some quite beautiful gemstones, including amazonite, spessartite, phenakite etc.

Hi Amanda,I suspect that your major interest is in determining whether the stone is synthetic or natural.  As synthetic corundum and even synthetic star corundum is not uncommon, this probably means a microscopic examination of the inclusions in the stone.  Such an examination can also ...

Are you sure it can scratch glass.  If so, it's unlikely to be Scheelite.

I'd vote for rutile--possibly Graves Mountain, GA.

I think there is a distinction between a mineral being sensitive to heat shock and the inclusions in the mineral posing a threat due to thermal expansion.  When gems (sapphires, beryls, tourmaline, zircon...) are being heat treated, it is critical to ensure that they are free of visible ...

Different region--and pezzottaite is definitely more pink than red. 

Definitely not corundum or tourmaline--hardness is near 8.  Some of the fragments do seem to possess at least partial hexagonal symmetry.  Also, while this pegmatite does produce rubellite--the appearance and crystal form are quite different.  No corundum has been found associated ...

My apologies for poor photography are warranted, but it will give you an idea.  Box containing crystals and fragments is about 76 mm on a side.  Largest fragment is about 12x10 mm.  I tried to photograph the samples on a white background, but my crappy little cell camera tended to ...

I will try to get some photos tomorrow.  I'll apologize in advance for the quality of the photos.  Most of the specimens are albite with a thin layer of red beryl.  In some cases, it appears to be the layer of beryl by itself. However, there are a few small crystals with roughly ...

I just got back from a short trip to Madagascar.  While there, I came across several small lots of what was being called "red beryl" or "bixbite".  Of course, I was skeptical.  The specimens looked quite a bit different from the Utah specimens I've seen.  And the matrix was a ...

As noted above, taaffeite is pretty rare.  Until recently, it was mostly mistaken for spinel, with the main distinguishing characteristics being RI and crystal form (for rough that wasn't too stream-worn).  I've found a few taaffeites in parcels of rough "spinel" I obtained in Ratnapura.I ...

Which shows you might want to attend will depend on what your specific interests may be.  If you are passionate about fluorescent minerals, you shouldn't miss the various shows in Franklin/Sterling/Ogdensburg, NJ.  If you are passionate about rutile, Graves Mountain is the don't miss ...

Cheaper does not mean "affordable".  And the opportunities for self collecting specimens are diminishing all the time.   I go to a lot of smaller shows, and there are always kids there looking longingly at all the pretty rocks and walking away sad that they can't afford ...

Ah, POR.  The translation of which is: "If you have to ask, it's too much."  I can't imagine any kids walking away from this show thinking that collecting minerals would be in any way a feasible or fulfilling hobby, unless they arrived with their parents in a Bentley.

Keith,That book is a gem in and of itself--full of mineral love stories and not just mineral porn.  A good friend is one of the collectors featured

Do you know where in Russia?  Some  Russian locations do have phenakite associated with beryl.  Any fluorite on the specimen, perhaps?  Could also be apatite from the crystal form and luster.  Definitely not emerald, though.  

Given that zircons are critical for dating rock layers, I would expect just about any paleo-geologist would be interested.  I've collected zircons from a variety of localities--Brazil, Sri Lanka, Nigeria, Madagascar, and thinks to a trade with Dean Allum (Thanks, Dean!), my home state of ...

One time in Sri Lanka, I saw a sapphire crystal with a quartz inclusion--and the quartz had an en hydro.

This may happen as the Ouro Preto mines are in decline.  However, I've yet to see the best Katlang stones rivaling even the middling stones from Ouro Preto.

Not the greatest photo, but his will give you some idea of the photo.  Color is better in person

Greg,  While it is certainly true that the term "imperial" topaz is a marketing term more than a technical designation, part of the issue is the sheer volume of material that has come from the Ouro Preto claims.  Any region that dominates production is going to wind up having an outsized ...

Just received a phosphophyllite from the Huayllani mine.  It is a nice specimen and a good complement to my specimen from Unificada, but some portions have a bit more limonite than I'd like.  I'm reluctant to use Super-Iron-Out (SIO), as it can be rather harsh on a specimen.   ...

Densit and hardness are probably best bet to distinguish phenakite from the most likely fakes (e.g. quartz).  Phenakite is a little harder than quarts, and so should scratch quartz.  Also about 10% denser than quartz.  Good luck.

I agree that thematic sub-collections often arise from opportunity.  I've been lucky enough to visit Sri Lanka several times and have accumulated a pretty good number of sapphire crystals.  So, I grouped them to highlight the different crystal habits, twinning and colors of the island's ...

Franz and Ralph raise important points.  A melt or hydrothermal solution may be rich in SiO2 or  Be3Al2(Si6O18) , but until it crystalizes it is not quartz or beryl.  Depending on temperature and pressure, SiO2  can crystalize as quarts, cristobalite, tridymite...

Susan,Reading those diagrams takes a bit of familiarity with the materials.  Basically, the diagrams represent a "family" if different minerals that have similar structure/chemistry.  At the corners of the triangle are the pure "end members".  In between, you have the chemistry of ...

Hi Susan, I'm sorry, those geological diagrams are downright misleading if you don't know what you are looking at. Rather than detailing the proportions of minerals that make up other minerals, they are really giving an idea of the elemental composition of a particular specimen relative to the ...

Ed, I've seen pure crystal clear topaz from Brazil, as well as very light blue due to color centers.  This color, though on my screen looks almost violet, and I haven't seen that.  The thing you definitely don't see with topaz: conchoidal fractures.

I agree that is unlikely to be topaz.  I didn't see a single cleavage plane in that video.  Odd because white topaz is quite common and inexpensive in Brazil.  Hard to believe anyone would go to the trouble.

At this point it's at the point of a "not-very-bright" undergrad with a tendency to understudy and try to make up for it by bullshitting on the exam questions. So, it has indeed learned from humans.

That's the nice thing about publishing--death doesn't silence your voice.  The laws of robotics are looking increasingly essential.

And it's not just malware.  Not long ago, some researchers harnessed an AI program used to generate possible new drugs to be investigated.  A few tweaks and it started generating possible neurotoxins--including several that are already known nerve agents with potential military ...

Rutherford mine was the place for microlites--they almost belied the "micro" in the name.  I miss Labor Days collecting there.

I first came across this tendency when one of the PhD students I'm advising asked ChatGPT about his own research area, which involves Bayesian probability.  In response to the initial question, the bot provided a reasonable, Wikipedia-level response.  When asked to actually construct a ...

samples on the right show good crystal form on 5 of 6 sides, middle, less well crystalized, but still euhedral. On the left, fragments, but good faces.  

Except spinels are pretty tough, and those look like they've been worn quite a bit.