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INTRODUCTION
Identification of Rasadravya (herbo-mineral substances) is a crucial step in Ayurvedic pharmaceutics, especially due to the increasing unavailability and adulteration of genuine substances (Jagtap et al., 2024). In Classics, Acharya mentioned detailed methodologies for identifying Rasadravya based on Grahya Lakshana (the physical and chemical characteristics) (Kulkarni, 2010; Sharma, 2000a).
Gairika, one of the Uparasa (secondary minerals), has been traditionally used in the treatment of various diseases (Sharma, 2000b). Acharya mentioned Shonita (red colour), Masruna (soft and smooth), Snigdha (unctuous), and Atikomala (very soft) Lakshana for the identification of Gairika (Kulkarni, 2010; Sharma, 2000a). According to the Ayurvedic Pharmacopoeia of India (API), authentic Gairika (Red Ochre) must contain not less than 16% elemental Iron or 21% Ferric Oxide (Fe₂O₃) (Government of India, 2009). Therefore, proper identification and standardisation of Gairika is essential before it is incorporated into any medicinal preparation.
The identification of Gairika holds great significance, as its Grahya Lakshana and iron content may vary according to geographical origin. Hence, mere reliance on physical observation is inadequate; a multidisciplinary approach integrating classical parameters with modern analytical techniques becomes essential for its precise characterisation.
In the present study, multiple samples of Gairika were collected from different regions. Each sample was evaluated for its authenticity and quality using a combination of classical identification methods (Grahya Lakshana), geological identification techniques (Lumen Learning, 2025) and modern instrumental methods, such as X-ray fluorescence (Neikov & Yefimov, 2019).
The study aims to identify a genuine sample of Gairika through classical and modern analytical methods, and to validate its purification process (Shodhana), thereby ensuring its safety and efficacy for therapeutic use by adopting the structural analysis by X-ray fluorescence, X-ray Diffraction and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy.
MATERIALS AND METHODS
A total of ten Gairika (Red Ochre) samples were collected from various pharmacies located in Mumbai, Delhi, Bangalore, Kadakola, Bagalakote, Kolhapur, Vashi, Belagavi (local), and two different sources within Belagavi. Initially, all samples were evaluated based on Grahya Lakshana as described in the classical Ayurvedic texts, Rasaratna Samuccaya and Rasatarangini (Kulkarni, 2010; Sharma, 2000a).
Subsequently, all ten samples were submitted to the Department of Geology, G.S.S. College, Belagavi, for geological identification. Based on the results obtained from the Department of Geology, including iron percentage determined by the titrimetric method (Research Gate, 2025) and geological identification, three samples were selected for further analysis using X-ray Fluorescence (XRF) at the Department of Chemistry, Rani Chennamma University, Belagavi, to estimate their iron content.
Based on the results of Grahya Lakshana and iron content analysis, the sample from Bagalakote was selected for the Shodhana (purification) procedure after assessing the microbial contamination. The Shodhana process was conducted using the Bharjana (roasting) method described in the Ayurveda Prakasha (Madhava, 2007).
For the Shodhana procedure, 750 g of Gairika was finely powdered and passed through a 120-mesh sieve. Out of this, 700 g were used for Shodhana. As per classical previous research, one-fourth of the quantity of Ghrita (clarified butter), i.e., 175 g, was used. (Charde et al., 2023; Ranade, 2022). An iron pan (Loha Kadhai) was heated on a low flame, and Ghrita was added until it melted. The powdered Gairika was then gradually added and roasted (Bharjana) until it became free-flowing and a distinct colour change was observed from dark red to brownish-red, accompanied by the characteristic aroma of Ghrita.
The duration of the process was 3 hr. After 3 hr, the purified Gairika was taken from the flame and allowed to cool. The purified Gairika was then filtered through a mesh and stored in an airtight container.
Then Shodhita Gairika was subjected to instrumental analysis, wherein XRF was selected to determine the percentage of elemental iron and iron oxide (Fe₂O₃), XRD and SEM-EDX for the structural characterisation.
Observations and Results
The samples collected from Mumbai, Bagalakote, Kolhapur, and Vasi passed all the Grahya Lakshana. The sample collected from Delhi was hard like stone; therefore, it did not pass the Atikomal parameter. The sample collected from Kadakola was hard and non-lustrous. Samples 1 and 3 from Belagavi did not pass these parameters. The second sample of Belagavi passed Masruna and Atikomal parameters. The results are presented in (Table 1, Figure 1).
| Sample Collected from | Shonita | Masruna | Snigdha | Atikomal |
|---|---|---|---|---|
| Mumbai | + | + | + | + |
| Delhi | + | + | + | - |
| Bengauru | + | + | + | + |
| Kadakola | + | + | - | - |
| Bagalakote | + | + | + | + |
| Kolhapur | + | + | + | + |
| Vasi | + | + | + | + |
| Belagavi (1) | - | - | - | - |
| Belagavi (2) | - | + | - | + |
| Belagavi (3) | - | - | - | - |
The mineralogical identification of all ten Gairika samples was carried out in the Geology Department of G.S.S College, Belagavi. The different parameters were tested for identification. The results are presented in (Table 2 (a) and Table 2 (b), Figure 1).
| Samples/ Parameters | Gairika Mumbai | Gairika Delhi | Gairika Bangaluru | Gairika Kadakola | Gairika Bagalakote |
|---|---|---|---|---|---|
| Colour | Brick red | Brownish red | Brick red | Light Brown | Deep Red |
| Hardness | Soft | Moderately hard | Soft | Soft to moderately hard | Soft to moderately hard |
| Lustre | Earthy | Earthy | Earthy | Earthy | Earthy |
| Streak | Red | Red | Red | Red | Cherry Red |
| Texture | Fine-grained and smooth to powdery | Fine-grained, slightly gritty | Fine-grained and smooth to powdery | Fine-grained and smooth to powdery | Fine-grained, slightly gritty |
| Opacity | Opaque | Opaque | Opaque | Opaque | Opaque |
| Composition | Hematite | Hematite | Hematite | Hematite | Hematite |
| Mineralogy | Clay mineral, quartz | Clay mineral, quartz | Clay mineral, quartz | Clay mineral, quartz | Clay mineral, quartz |
| Solubility | Insoluble in water | Insoluble in water | Insoluble in water | Insoluble in water | Insoluble in water |
| % of Iron content | 15.9% | 12.17% | 14.9% | 11.85% | 24.68% |
| Samples/ Parameters | Gairika Kolhapur | Gairika Vasi | Gairika Belagavi (1) | Gairika Belagavi (2) | Gairika Belagavi (3) |
|---|---|---|---|---|---|
| Colour | Deep Red | Deep Red | Light brown pink | Light Red | Light brown |
| Hardness | Soft | Soft | Hard | Moderately Hard | Moderately Hard |
| Lustre | Earthy | Dull | Dull | Dull | Dull |
| Streak | Cherry Red | Cherry Red | Brown | Light Red | Light Brown |
| Texture | Fine-grained, Smooth | Fine-grained, Smooth | Fine-grained, slightly gritty | Fine-grained, Smooth | Fine-grained, slightly gritty |
| Opacity | Opaque | Opaque | Opaque | Opaque | Opaque |
| Composition | Hematite | Hematite | Hematite | Hematite | Hematite |
| Mineralogy | Clay mineral, quartz | Clay mineral, quartz | Clay mineral, quartz | Clay mineral, quartz | Clay mineral, quartz |
| Solubility | Insoluble in water | Insoluble in water | Insoluble in water | Insoluble in water | Insoluble in water |
| % of Iron content | 23.4% | 20.4% | 05.97% | 07.48% | 10.75% |
The results obtained from the mineralogical identification showed that among 10 samples, 3 samples had an iron content above 20%. These three samples were further submitted for the XRF analysis. The results are presented in (Table 3).
| Sl. No. | Metals/ Minerals | % of the Composition | Oxides | % of the Composition | ||||
|---|---|---|---|---|---|---|---|---|
| Sample 5 | Sample 6 | Sample 7 | Sample 5 | Sample 6 | Sample 7 | |||
| 1 | Fe | 22.85±0.11% | 24.97±0.11% | 21.54±0.09% | Fe2O3 | 73.2±0.6% | 75.3±0.6% | 76.7±0.6% |
| 2 | K | 0.59±0.25% | 0.6±0.3% | 0.4±0.3% | SiO2 | 14.1±0.7% | 12.1±0.6% | 12.1±0.6% |
| 3 | Ti | 0.53±0.10% | 0.46±0.10% | 0.52±0.09% | Al2O3 | 10.5±1.3% | 10.1±1.3% | 8.7±1.3% |
| 4 | Cr | 0.03±0.03% | - | - | TiO2 | 1.21±0.22% | 1.07±0.22% | 1.29±0.23% |
| 5 | Ba | - | 0.09±0.21% | - | P2O5 | 0.2±0.3% | 0.2±0.3% | 0.2±0.3% |
| 6 | Sb | - | 0.04±0.05% | - | CaO | 0.2±0.3% | 0.1±0.3% | - |
| 7 | Sn | - | 0.02±0.02% | - | PdO | 0.10±0.04% | - | - |
| 8 | Zr | - | 0.02±0.00% | - | ZrO2 | 0.10±0.01% | 0.10±0.01% | 0.13±0.01% |
| 9 | V | - | 0.03±0.04% | BaO | 0.1±0.4% | 0.1±0.4% | - | |
| 10 | Sb2O3 | 0.08±0.19% | - | - | ||||
| 11 | V2O5 | 0.06±0.12% | 0.05±0.12% | 0.07±0.12% | ||||
| 12 | Nb2O5 | 0.03±0.01% | 0.03±0.01% | 0.03±0.01% | ||||
| 13 | PbO | 0.03±0.01% | 0.03±0.01% | - | ||||
| 14 | SrO | 0.02±0.01% | 0.02±0.01% | 0.02±0.01% | ||||
| 15 | NiO | - | 0.02±0.04% | - | ||||
| 16 | K2O | - | 0.7±0.4% | 0.7±0.4% | ||||
| 17 | SnO2 | - | - | 0.10±0.11% | ||||
| 18 | Ta2O5 | - | - | 0.06±0.05% | ||||
| 19 | Rb2O | - | - | 0.02±0.01% |
Ghee was analysed as per the API for its quality. The results are presented in (Table 4).
| Tests | Limits | Results |
|---|---|---|
| Organoleptic Characters | ||
| Form | Semisolid with granular texture | Semisolid with granular texture |
| Colour | White to light yellow | White to light yellow |
| Odour | Rich and Characteristic | Rich and Characteristic |
| Taste | Pleasant | Pleasant |
| Physicochemical standards | ||
| Moisture content | Not more than 0.5% | 0.048% |
| Weight per ML | NA | 1.012 |
| Acid value | NA | 3.899 |
| Saponification value | Not more than 225 | 201.153 |
| Iodine value | Not more than 35 | 32.474 |
| Specific gravity | NA | 0.956 |
| Rancidity | NA | Negative |
The Gairika Sample was evaluated for microbial contamination before the Shodhana procedure. The results are presented in (Table 5).
| Test for specified Micro-Organisms (Qualitative) | ||
|---|---|---|
| Limits (As per IP) | Results | |
| E. coli | Absent/100 mL | Absent |
| S. aureus | Absent/100 mL | Absent |
| P. aeruginosa | Absent/100 mL | Absent |
| S. Abony | Absent/100 mL | Absent |
| Microbial Limit Test (Quantitative) | ||
| Total Bacterial Count | 30 - 300 cfu/mL | No growth |
| Total Fungal Count | 10 - 100 cfu/ml | No growth |
The Gairika Shodhana process details are presented in (Table 6).
| Gairika Shodhana | Gairika | Go Ghrita | Duration | Quantity obtained | Weight Gain |
|---|---|---|---|---|---|
| 700 g | 175 g | 3 hr | 824.2 g | 124.2 g |
The organoleptic evaluation of Gairika before and after Shodhana is presented in (Table 7 and Figure 2).
| Organoleptic characters | Before Shodhana | After Shodhana |
|---|---|---|
| Colour | Deep red | Reddish brown |
| Touch | Soft | Soft |
| Odour | Muddy | Ghrita gandha (Ghee odour) |
| Taste | Kashaya | Kashaya Madhura |
The Gairika was evaluated for its chemical composition before and after the Shodhana in Go Ghrita by XRF. The results are tabulated in (Table 8).
| Sl. No. | Metals/ Minerals | % of the Composition | Oxides | % of the Composition | ||
|---|---|---|---|---|---|---|
| Before Shodhana | After Shodhana | Before Shodhana | After Shodhana | |||
| 1 | Fe | 26.4±0.05% | 21.7±0.04% | Fe2O3 | 73.8±0.6% | 73.1±0.6% |
| 2 | Ti | 0.55±0. 05% | 0.5±0. 04% | SiO2 | 13.3±0.6% | 14±0.6% |
| 3 | K | 0.44±0.13% | 0.33±0.12% | Al2O3 | 10.6±1.2% | 10.8±1.3% |
| 4 | Ca | 0.06±0.06% | 0.07±0.05% | TiO2 | 1.09±0.22% | 1.13±0.22% |
| 5 | Cr | 0.02±0.01% | 0.01±0.01% | K2O | 0.5±0.4% | - |
| 6 | V | 0.02±0.02% | 0.02±0.01% | P2O5 | 0.2±0.3% | 0.2±0.3% |
| 7 | Zr | 0.02±0.00% | 0.01±0.00% | CaO | 0.1±0.3% | 0.1±0.3% |
| 8 | Mn | 0.02±0.00% | 0.02±0.00% | ZrO2 | 0.11±0.01% | 0.11±0.01% |
| 9 | Pb | 0.005±0.00% | 0.00±0.00% | V2O5 | 0.05±0.11% | 0.05±0.12% |
| 10 | Sr | 0.004±0.00% | 0.00±0.00% | Cr2O3 | 0.03±0.05% | 0.04±0.05% |
| 11 | Rb | 0.003±0.00% | 0.00±0.00% | Nb2O5 | 0.03±0.01% | 0.03±0.01% |
| 12 | Br | 0.0005±0.00% | - | Rb2O | 0.02±0.01% | - |
| 13 | L.E | 72.42±0.1% | - | SrO | 0.02±0.01% | - |
| 14 | Sn | - | 0.02±0.01% | Ga2O3 | 0.01±0.01% | - |
| 15 | Mo | - | 0.00±0.00% | Co3O4 | - | 0.09±0.14% |
| 16 | Se | - | 0.00±0.00% | BaO | - | 0.1±0.4% |
| 17 | ThO2 | - | 0.05±0.03% |
The structural characteristics of Gairika were evaluated before and after Shodhana in Go Ghrita using XRD and the findings are presented in (Table 9, Graphs 1a, 1b).
| Parameter | Aśhodhita Gairika | Shodhita Gairika |
|---|---|---|
| Major peak (2θ, d-spacing) | 12.35° (7.15 Å), 24.87° (3.57 Å), 33.14° (2.70 Å), 62.38° (1.48 Å) | 12.52° (7.06 Å), 33.27° (2.69 Å), 62.53° (1.48 Å) |
| Peak intensity (gross counts) | Strong peak at 12.35° (97.37 cps), 24.87° (88.34 cps) | Reduced peak intensity, 12.52° (18.86 cps) |
| Crystallite size | 76.7 nm (12.35°), 65.9 nm (24.87°), 12.2 nm (33.14°), 19.0 nm (62.38°) | 41.1 nm (12.52°), 11.6 nm (33.27°), 19.3 nm (62.53°) |
SEM-EDX
The structural characteristics of Gairika were evaluated before and after Shodhana in Go Ghrita using SEM-EDX and the findings are presented in (Graphs 2a, 2b, Figures 3a, 3b).
DISCUSSION
The identification of Rasadravya, especially mineral substances like Gairika (Red Ochre), is crucial for ensuring the safety, efficacy, and authenticity of Ayurvedic formulations. Classical texts such as the Rasaratna Samuccaya and Rasatarangini describe the Grahya lakshana (a set of physical and chemical tests) precisely for recognising genuine Rasadravyas (Kulkarni, 2010; Sharma, 2000a). However, in modern science, with increasing adulteration and regional variations in mineral composition, traditional methods need to be complemented with contemporary scientific tools to verify the authenticity of Rasadravya.
In the present study, ten samples of Gairika were collected from various geographic regions across India and subjected to an analytical approach, including classical Grahya lakshana assessment, geological evaluation, and instrumental analysis using XRF. This approach emphasises the importance of integrating ancient wisdom with modern science for accurate identification and standardisation.
Out of ten collected samples, six met all four key Grahya Lakshana (Shonita, Masruna, Snigdha, Atikomal), indicating potential suitability for therapeutic use. Samples from Delhi, Kadakola, and two Belagavi sources failed to meet these criteria, suggesting impurity or a non-standard mineralogical composition. This underscores the importance of Grahya Lakshana as a first-level screening tool in Ayurvedic pharmaceutics.
Geological characterisation revealed hematite as the primary mineral constituent in all samples, accompanied by secondary minerals such as clay and quartz. Despite uniform mineralogy, iron content varied significantly among the samples. Only samples from Bagalakote, Kolhapur, and Vasi surpassed the API's minimum requirement of 16% of Iron content, underscoring that visual assessment alone is insufficient to confirm authenticity. A deep red colour correlated with higher iron content, aligning with the classical reference to Shonita (blood-like red colour) as a desirable trait. The samples had lower concentrations of iron oxides, which are often used in industrial settings rather than directly for medicinal purposes because of their low nutrient bioavailability.
XRF analysis further confirmed the high Fe₂O₃ content in the Bagalakote (73.2%), Kolhapur (75.3%), and Vasi (76.7%) samples. These values significantly exceed the API threshold, affirming their authenticity. Additionally, the presence of trace elements like Ti, K, and Si, along with oxides such as Al₂O₃ and SiO₂, reflects the natural heterogeneity of mineral samples. Importantly, toxic heavy metals such as Pb and Cr were found in negligible quantities, ensuring safety for pharmaceutical use.
Among the three quality passed samples, the Bagalakote sample was selected for Shodhana based on both classical parameters and iron content. The selected sample of the Gairika passed all microbial contamination tests. The Bharjana method using Go Ghrita (clarified butter) was chosen, as mentioned in Ayurveda Prakash. Post Shodhana, the Gairika showed notable changes in organoleptic properties, colour changed from deep red to reddish-brown, and the characteristic smell of Ghrita was imparted. These changes indicate a successful transformation, aligning with classical expectations of Shodhana.
XRF analysis after Shodhana revealed a decrease in elemental iron from 26.4% to 21.7% and a marginal reduction in Fe₂O₃ from 73.8% to 73.1%. This minor reduction could be attributed to the thermal and oxidative interactions during Bharjana, possibly causing superficial loss or redistribution of iron compounds, phase transformation, and surface-level redistribution of iron species.
The XRD analysis of Ashodhita Gairika demonstrated sharp and intense peaks with high counts, confirming its higher degree of crystallinity and relatively larger crystallite size. In contrast, Shodhita Gairika exhibited peaks of reduced intensity and slight broadening, accompanied by marginal shifts in 2θ values. These changes indicate a reduction in crystallinity, partial amorphisation, and lattice modifications induced by the Shodhana process.
A noteworthy observation was the decrease in crystallite size following Shodhana. The crystallite dimension, which was as high as 76.7 nm in Ashodhita Gairika, reduced to 41.1 nm in Shodhita Gairika at the corresponding peak (12.35° vs 12.52°). This refinement towards smaller particle sizes suggests that Shodhana in Go Ghrita facilitates particle disintegration and enhances surface area. Such a transformation is pharmaceutically significant, as finer and less crystalline particles are known to exhibit improved bioavailability and reactivity, thereby potentiating the therapeutic effects of mineral drugs.
SEM results of Ashodhita Gairika revealed an irregular, and heterogeneously aggregated structure. In contrast,Shodhita Gairika showed auniform, compact, and finely granulated microstructure.
The EDAX spectrum of Ashodhita Gairika showed Fe and O as the dominant elements, confirming Iron Oxide (Fe₂O₃) as the principal component. Peaks corresponding to Si, Al, C and other trace elements were also noted, indicating the presence of siliceous and organic impurities naturally associated with mineral deposits. After purification, Shodhita Gairika exhibited a higher relative intensity peak of Fe, while peaks associated with Si, Al, and carbonaceous impurities showed significant reduction. This confirms that Shodhana effectively removed the impurities.
CONCLUSION
This study underscores the necessity of a comprehensive, multidisciplinary approach for identifying and standardising Gairika. While Grahya Lakshana remains foundational, geological and instrumental analyses such as titrimetric, XRF, XRD and SEM EDX assessments are indispensable for confirming elemental composition and ensuring compliance with pharmacopoeial standards. The selected sample from Bagalakote demonstrated both classical and modern acceptability, and its Shodhana process further enhanced its organoleptic and safety profile without compromising its mineral integrity.
The integration of traditional Ayurvedic wisdom with modern analytical techniques enhances confidence in the authenticity, safety, and therapeutic potential of Rasadravyas like Gairika. This approach may serve as a model for the standardisation of other herbo-mineral drugs in Ayurvedic pharmaceutics in future research.