Whilst shopping at my favourite shop, Kremer Pigmente for some aerinite, I came across a mineral pigment I did not know, and obviously just had to buy it. It is called pentagonite, and Kremer indicate that it is sourced in Goa, India.
Well, the bottle of pale, turquoise blue pigment has arrived. I’ve made a grain dispersion and have just had a look under the microscope … and disappointingly, it is colourless in plane polarised light with low birefringence under crossed-polars. However that is not a surprise, because pentagonite is that unusual thing, a silicate mineral that can be used as a pigment. Many silicates, however colourful in hand specimen do not retain their colour when finely ground. Anyone who has done Minerals 101 will remember the streak test. A mineral that gives a good ‘streak’ when chalked onto fired, unglazed tile is also likely to be a good pigment. Most silicates give a white streak. Pentagonite is calcium vanadium silicate (Ca[VO]Si4O10.4H2O).
As I bought it on a wh
im, I never bothered to check out what it was until now. I was slightly cheered here as I realised that I am aware of a polymorph called cavansite. There is much to be said on the naming of minerals, but CaVanSite is boringly named after its constituent elements. I feel the mineral namers missed a trick here as it is my wish to discover a new mineral and call it caravansite. For a split second, when I spotted the cavansite at a mineral dealers, I thought someone had beaten me to it. So I bought that on a whim too. Pentagonite and cavansite were first discovered in Oregon, USA, found infilling cavities and fissures in flood basalts. The minerals have been found in the same environment in the Deccan Traps of Southern India.
I would be really grateful to know if any artists have used this material and if so what they thought of it as a pigment?
©Ruth Siddall 2015
Orpiment 
As a worker in metaphysics, i cringed, and almost cried upon reading this. I suppose its the choice of whomever purchases it, as to what they wish to use it for. Personally, I handle all of my stones, crystals, minerals and fossils with the most vigilant of gracefulness, as to not compromise any fine detail. For us, there is so much more than simple pigment. There are firstly, the details concerning the age of the specimen…how long…how much, or how wise, this specimen is. Each one can, and will tell you its story, as an energetic, sentient being. Of course, not all are yet ready to listen. Understandable. All have these abilities within us (just take intuition, for example…that, is your first ability to build upon), we need only to practice and work at it, much like learning an instrument, the ability is there. Second, each piece has such glorious metaphysical properties. I highly suggest, even if its for entertainment value, for you to do a simple google search to find the very rare gifts of this lovely crystal that you have pounded into powder. Im crying. ( no, not seriously, i am simply jesting from one side of the fence to the other)
There honestly arent even many within the spiritual community that know of this mineral. (Personally, i am both spiritualist and geologist amateur, i love all aspects, secrets, that Gaia holds inside) Yes, those of us that love them do learn the chemical composition, general uses, along with toxicity levels, the streak test and, of course, how rare they are….and this one, my dear, is very rare. So, ,please, take great pleasure in using your so called boring color in your work…bring it to life with amazing creativity….then, when finished, if you decide to sell…dont forget to advertise within the metaphysical, or spiritual, even new age, community, and along with your description of the work, use it as a selling point…it will be sold for just about any asking price within moments.
I know i did not answer your question, but, it is human to comment, to share our words, with as many as we can.
Love and blessings to you!
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Hi, I’ve used this material in some reproductions. In the pyrenees of Spain there are some deposits of aerinite, and it was used in the past for painting some blue backgrounds in romanesque frescos because of the high price of lapis lazuli. You can take a look of how this pigment looks if you type in google: Pantocrator Taull.
https://en.wikipedia.org/wiki/Apse_of_Sant_Climent,_Ta%C3%BCll
The aerinite pigment is always applied over a black ivory field in fresco technique.
Regards, Jorge.
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