- Most commercial resin is made by water extraction: dissolve, settle, filter, then dry.
- “Purified” has no legal or technical definition on a UK label. It describes a process the seller chose, not a standard met.
- Purification removes insoluble debris well. It does not reliably remove dissolved metals: one analysis found some supplements had more thallium than raw samples.[1]
- The human trials used purified or standardised preparations, not raw material.[2][3]
Why raw shilajit is processed
Material scraped from a rock face is not a finished product. It contains insoluble rock and sand, plant fragments, varying moisture and whatever microbes collected on it during gathering and storage. Processing aims to remove the solids, standardise the texture and moisture, and reduce microbial load. It also makes the product look the way buyers expect: glossy, uniform and dark. Appearance and safety are different goals, which is why the method matters.
The typical commercial process
- SortingVisible stone and debris are removed from the raw material.
- DissolvingThe material is soaked in water, often over several days, so the soluble fraction goes into solution.
- Settling & filteringInsoluble solids sink or are filtered out. Some producers repeat this several times.
- ConcentratingWater is removed by sun, gentle heat or vacuum until a thick resin remains.
- FinishingThe resin is packed, or dried further and milled into powder for capsules.
Producers vary the order, number of cycles and drying method. See water-based extraction explained and how commercial resin is produced.
Drying methods compared
Drying is where producers make the biggest trade-offs between time, cost, appearance and microbial control. The method is rarely stated on UK labels, but it is a reasonable question to ask.
| Method | How it works | Trade-off |
|---|---|---|
| Sun-drying | Extract left in open trays to evaporate | Cheap and traditional, but slow, with little control over dust, insects or microbes |
| Low-heat evaporation | Gentle heating in vessels | Faster and more controlled; heat level and duration vary by producer |
| Vacuum evaporation | Water removed at reduced pressure and lower temperature | Better control; needs equipment |
| Spray- or freeze-drying | Extract turned into powder | Used for powders and capsules; carriers may be added |
“Sun-dried” is a selling point, not a quality marker. See “wild-harvested”, “sun-dried” and “raw” claims, does heat affect shilajit? and does drying change shilajit?
What “purified” should mean
Because there is no standard definition, “purified” is only as meaningful as the evidence behind it. A purification claim is credible when the seller can say what was done and show what it achieved:
- The process is describedNumber of extraction cycles, filtration method and drying method.
- Results are batch-specificA COA for the batch on sale, not a one-off report.
- Contaminants were tested after processingMetals and microbiology on the finished product, not only on raw material.
- Nothing was addedOr, if carriers or fillers were added, they are listed on the label.
Our explainers on how shilajit is purified, “pure” and “purified” claims and raw vs purified go further.
What processing can’t fix
Water extraction is good at removing things that don’t dissolve. Metals bound to the soluble organic fraction can travel straight through it and end up concentrated in the dried product. That is one plausible reason why a 2025 study found some commercial supplements with higher thallium levels than the crude shilajit tested alongside them.[1]
Processing also can’t fix adulteration that happened earlier in the chain, or prove identity. Only testing of the finished batch shows what was achieved. See how purification can affect quality testing and laboratory testing.
Standardised extracts
Some ingredient suppliers go beyond basic purification and standardise their extract to fixed levels of selected components. Several of the published human trials used one such branded extract.[2][3] Standardisation makes batches more consistent and research easier to reproduce, but it also makes the product a different material from a whole resin. That’s why trial results for a standardised extract can’t simply be applied to resin. See standardised and branded extracts and standardised extract vs whole resin.
Questions to ask a seller about processing
- Who processes the raw material, and where?A named facility is easier to trust than “traditional methods”.
- How many extraction and filtration cycles?Shows how much effort goes into removing solids.
- How is it dried, and at what temperature?Affects microbial control and the final material.
- Is anything added?Carriers, flow agents or other ingredients should be on the label.
- Is the finished batch tested?Ask for the COA for your batch number. Request template
How collection and pre-processing work before any of this is covered in how shilajit is collected and prepared, and the effect on composition in how processing can affect composition.
Common questions
Is raw shilajit better than purified?
There is no evidence that it is, and unprocessed material is more likely to carry debris and microbes. The human trials used purified or standardised preparations. “Raw” on a label usually means minimally processed rather than unprocessed.
Does purification remove heavy metals?
Not reliably. It removes insoluble particles well, but dissolved metals can remain and even concentrate as water is removed. Only a test of the finished batch tells you.
Why does powder sometimes contain other ingredients?
Drying an extract into a free-flowing powder can require carriers or anti-caking agents. They must be listed on the label, and they reduce the amount of shilajit per gram. See shilajit forms.
Sources & further reading
Primary research, regulators and standards bodies are cited first. A source being listed here does not mean it supports every claim made by sellers; it supports the specific statement it is attached to.
- Quantifying of thallium in Shilajit and its supplements to unveil the potential risk of consumption of this popular traditional medicine. BMC Chemistry 19:20, 2025. doi:10.1186/s13065-025-01384-7. View source (opens in a new tab) [Laboratory analysis]
- Pandit S, Biswas S, Jana U, De RK, Mukhopadhyay SC, Biswas TK. Clinical evaluation of purified Shilajit on testosterone levels in healthy volunteers. Andrologia 48(5):570–575, 2016. PMID 26395129. View source (opens in a new tab) [Randomised controlled trial]
- Keller JL, Housh TJ, Hill EC, Smith CM, Schmidt RJ, Johnson GO. The effects of Shilajit supplementation on fatigue-induced decreases in muscular strength and serum hydroxyproline levels. Journal of the International Society of Sports Nutrition 16:3, 2019. doi:10.1186/s12970-019-0270-2; PMID 30728074. View source (opens in a new tab) [Randomised controlled trial]