Zi Shi Ying

Fluorite itself is pharmacologically inert; everything that matters is what fluoride it releases. CaF2 is very sparingly soluble in water (Ksp of order 1e-11 at 25 C, giving a saturated solution of roughly 16 mg/L, about 8 mg/L as fluoride), so a strained decoction delivers only a few milligrams of fluoride even though a 9 to 15 g dose contains 3.7 to 6.2 g of fluoride as bound mineral. That arithmetic is the whole safety argument for this drug, and it collapses if the mineral is swallowed rather than strained out: in pills and powders the solid enters the stomach, where hydrochloric acid attacks CaF2 to liberate hydrogen fluoride and free fluoride ion.

Absorbed fluoride is distributed to bone and teeth, where it substitutes for hydroxyl in hydroxyapatite to form fluorapatite, and is cleared almost entirely by the kidney. Chronic excess produces dental fluorosis and then skeletal fluorosis — osteosclerosis, ligament and interosseous membrane calcification, joint pain and stiffness, and in advanced disease crippling deformity and radiculopathy. The relevant benchmark for chronic intake is the EFSA adequate intake for fluoride from all sources of 0.05 mg per kg body weight per day, which for a 60 kg adult is 3 mg per day, against a background that already includes water, tea and toothpaste.

Han et al. reviewed the coloration mechanism of fluorite in relation to the Pharmacopoeia's colour specification: the green derives from a colour centre generated by Sm2+ with compensating sodium-ion centres (absorption at 570 and 305 nm), the yellow from charge transfer involving transition-element substitution, and dark varieties from evolved organic matter within the crystal. Because the Pharmacopoeia specifies purple or green while white and yellow material is common in the market, the colour rule is functioning as an unstated impurity specification, and the authors propose revising it. Toxicologically the lanthanide load of medicinal fluorite has not been quantified.

The practical finding is that processing is not purification. Traditional vinegar quenching and water-flying leave the CaF2 content essentially unchanged (RSD 1.61 percent across processed forms) while measurably increasing the trace-metal load — zinc appearing where none was detectable before. Whatever the classical rationale for 醋淬, it does not make the drug cleaner in the elemental sense.

Calcining to redness and quenching in vinegar cracks the crystal and leaves acetate on the fracture surfaces, giving a finer, more uniform particle (RSD 18.9 percent) with far more surface area. A finer, acid-etched particle with soluble surface calcium is a more soluble particle, so the processing that tradition regards as reducing toxicity plausibly increases the fraction of fluoride available in the stomach. No one has measured this.

Fluorite is a standard gangue and ore mineral of carbonate-hosted lead-zinc deposits, so galena (PbS) and sphalerite (ZnS) are common companions in the rock the drug is picked from. This is a geological expectation, not a measurement: there is no published elemental survey of commercial Zi Shi Ying reporting arsenic, lead, cadmium or mercury. The absence of an assay is not evidence that the load is low.

Recorded plainly because it is a real gap rather than a reassurance. ChP 2020 removed the blanket heavy-metals provision and instead applies element limits to named individual medicinal materials — a list of plant drugs — so mineral drugs including Fluoritum fall outside it, even though the general methods (2321 for lead, cadmium, arsenic, mercury and copper; 0821 and 0822 for heavy metals and arsenic) exist and could be applied. A practitioner therefore has an assay guaranteeing what fraction of the drug is calcium fluoride, and no guarantee at all about what the other 15 percent is.

Source of first record, where Zi Shi Ying is placed among the upper-grade jade-and-stone drugs — the class held to be non-toxic and suitable for prolonged use. That classification is a historical fact about the text, not a safety finding, and it is precisely the classification that invites the months-long courses under which fluoride accumulates.

Expands the indications toward uterine cold and infertility, the use for which the drug is still mainly prescribed. Together with the Ben Jing entry this establishes the classical profile as a warming, spirit-settling mineral rather than a purgative or topical one.

Feng Yin Tang combines rhubarb, dried ginger, dragon bone, cinnamon twig, licorice, oyster shell, Han Shui Shi, talc, red and white halloysite, shi ying and gypsum. The formula is the classical anchor for both this drug and Han Shui Shi, and its transmission illustrates the identity problem in this corpus: editions differ over whether the shi ying in the list is Zi Shi Ying (purple fluorite) or Bai Shi Ying (white quartz).

Describes the drug as clear as crystal with uneven purple colouring — a description that matches fluorite. Set against the Tang-period Ling Biao Lu Yi, which describes pale purple lustrous crystals with edges pointed like arrowheads and matches quartz instead, this is the textual root of the fluorite-versus-amethyst substitution still seen in Sichuan and Yunnan.

Settles the identity as the fluoride mineral fluorite, mainly CaF2, purple or green, with EDTA-titration assay limits of not less than 85.0 percent CaF2 raw and 80.0 percent for the calcined vinegar-quenched product; processing is calcination to redness with vinegar quenching at 30 kg vinegar per 100 kg drug; dose 9 to 15 g, decocted first. It sets no arsenic, lead, cadmium or mercury limit.