Stones reach a sign’s list by a few countable roads, and Taurus is where every one of them is in plain view. Emerald arrived by the calendar, because most of Taurus falls in May, and rose quartz by Venus, which rules the sign.
The oldest item on a modern Taurus list is not a stone. It is Venus. Ptolemy set out which planet governed which sign in the second century and handed Venus two of them, Libra and Taurus, and that is still the standard assignment more than eighteen centuries later. Everything else on the list is younger, and most of it is very much younger.
A list assembled across that kind of span can be taken apart. Five stones come across a counter for Taurus. Did they come from the same place?
They did not, and the roads can be counted. One is the calendar, since a sign covers a month and the month has a birthstone. Another runs through the ruling planet, because planets have had stones attached to them in print since the Renaissance and a sign inherits whatever its planet was given. The last is plain resemblance, a stone that looks like what the sign is supposed to be. None of them excludes the others.
Sorting the tray
Emerald arrives by the calendar. Taurus runs from about 20 April to about 20 May, so roughly two thirds of it sits in May, and May’s stone is emerald in the list Jewelers of America maintains. The organisation dates that list to 1912 and to the American National Retail Jewelers Association, the body it grew out of. Emerald therefore heads the Taurus list because of a decision a trade association took about a calendar month. The sign came into it afterwards.
The planet accounts for rose quartz. Venus rules Taurus, which is Ptolemy’s assignment and not a modern flourish, and crystal practice attaches rose quartz to Venus and to the things Venus is held to govern, love and unhurried pleasure. The first half of that route is very old. The second half is not, and the join between the two halves tends to vanish whenever a pink stone is described as the traditional stone of the bull.
Then there is resemblance, which is where jade and malachite come from. Both are green, both have real weight in the hand, and Taurus carries a reputation in practice for steadiness and for material comfort. Practitioners recommend them on exactly that basis and say so when asked. Neither recommendation rests on a document.
The roads overlap, and emerald is where the overlap runs thickest. It is May’s stone, and it is also green, the colour practice gives Venus, so it passes two tests before anyone has asked it a question. That redundancy is a plausible reason it has stayed at the head of the list while the stones under it have shuffled.
Where the test leaves sapphire
Sapphire answers none of the three. September is its month, so the calendar hands it to Virgo and to Libra. Modern practice does not put it with Venus. Green is the Taurus colour and sapphire is blue.
It is on the list because it was on an older one. George Frederick Kunz published a zodiacal list in 1913, in the compilation most modern accounts trace back to, and his entry for Taurus is sapphire. A century later sapphire is still on the Taurus list. Matches like that are rare enough to be worth counting, and the Aquarius page does the counting, twice, on two different definitions of a match.
The two older sources do not help it along. Cornelius Agrippa’s table of sign stones, printed in 1533, gives Taurus carnelian. A treatise printed at Valladolid in 1604, which Kunz reproduces with a proper citation and describes as probably representing Arab tradition, gives Taurus ruby and diamond. Neither of those answers is what a shop reaches for now, and none of the three old compilers agrees with either of the others about Taurus.
That is a fourth road, and it is transmission rather than reasoning. A stone is on the list because it was on the list before. It is also the shortest road anybody has measured. Kunz printed his zodiacal list without a reference of any kind, in a chapter where nearly every other assertion carries one. Nothing in any of this is a tradition of stones for the sign of the bull, and the nearest thing to one runs back to that page.
Underneath the five names
Beryl is the species behind emerald, which is only beryl that came out green: beryllium aluminium silicate, hexagonal, Mohs 7.5 to 8, cleaving imperfectly on the basal plane. Those figures make it sound hardier than it is. GIA rates emerald’s toughness fair to good and reports that some estimates put 90 per cent or more of emeralds as fracture-filled, the fractures treated with oil or resin so they read less clearly. Hot steam can sweat that filler back out, and ultrasonic vibration can weaken a stone that was already fractured. The method GIA gives as safest is warm soapy water and a gentle scrub, which is what most people were going to do anyway.
Rose quartz took a hundred years to explain. Goreva, Ma and Rossman, publishing in American Mineralogist in 2001, traced the pink of ordinary massive rose quartz to fibrous nanoinclusions of a material closely related to dumortierite, with the colour produced by an iron and titanium charge transfer inside those fibres. Earlier work had put the colour down to light scattering off rutile needles, and the 2001 paper displaces that. The fibres do scatter light, which is why massive rose quartz is always at least slightly cloudy, but the cloudiness is a symptom of the second phase rather than the source of the colour.
Jade is two rocks and one word. GIA uses jade as a generic term for nephrite and jadeite, admitting green omphacite under some conditions, and describes the materials as metamorphic rocks built from tiny interlocking crystals, which is what makes them exceptionally tough. Jadeite is a valid species, sodium aluminium silicate, monoclinic, Mohs 6 to 7, and very tough when massive. Nephrite is not a species at all. It is a felted aggregate of amphibole from the tremolite and actinolite series. Two different rocks arrive at the counter under one label, and the label is older than the distinction it hides.
Malachite is copper carbonate hydroxide, monoclinic, Mohs 3.5 to 4, with perfect cleavage on {201}, and it sits at the bottom of this list by a wide margin. Sapphire sits at the top of it, corundum being aluminium oxide at hardness 9, brittle but tough when compact, with partings rather than a true cleavage. Neither fact had anything to do with why either stone is on the list. Hardness and provenance are separate questions, and the list answers only one of them.
Malachite is also the only one of the five a person could look up in the Crystalance Mineral Library by the word on the price tag. Emerald is under beryl there, rose quartz under quartz, sapphire under corundum, and jade lands under jadeite or nowhere, depending on which of the two rocks is in the tray.
A shop does not label the tray with any of this, and there is no reason it should. The roads are still there to be read off, and on a Taurus list they are unusually easy to read, because the same stone sits on two of them at once.
Sources
- Ptolemy, Tetrabiblos I.17, Robbins translation, on the houses of the planets: penelope.uchicago.edu
- Jewelers of America, birthstones by month and the 1912 origin of the list: jewelers.org
- George Frederick Kunz, The Curious Lore of Precious Stones, 1913, chs. IX and X, for the zodiacal list and the 1604 Valladolid list: gutenberg.org
- Cornelius Agrippa, Three Books of Occult Philosophy, Book II ch. XIV, the Scale of the Number Twelve, in Peterson’s edition of the 1651 English translation of the 1533 original: esotericarchives.com
- GIA, emerald care and cleaning, on fracture filling and steam: gia.edu
- Handbook of Mineralogy, beryl: handbookofmineralogy.org
- Goreva, J.S., Ma, C., and Rossman, G.R., “Fibrous nanoinclusions in massive rose quartz: the origin of rose coloration”, American Mineralogist 86 (2001), 466 to 472: its.caltech.edu
- GIA, jade description: gia.edu
- Handbook of Mineralogy, jadeite: handbookofmineralogy.org
- Handbook of Mineralogy, malachite: handbookofmineralogy.org
- Handbook of Mineralogy, corundum: handbookofmineralogy.org
