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GYPSUM • INDUSTRIAL MINERAL

Gypsum Mineral Context & Buyer Specifications in Pakistan

Gypsum specifications in Pakistan require precise determination of calcium sulfate dihydrate (CaSO4·2H2O) purity, combined water, free moisture, chloride contamination, and size distribution. Industrial suitability varies significantly between cement set-retarders, calcined plaster of Paris, and agricultural soil amendments.

Primary Application
Cement Retarder / Plasterboard / Agriculture
Main Testing
Purity (CaSO4·2H2O % & Combined H2O)
Product Form
Screened Lump / Crushed Mineral / Powder
Evidence Category
Official Production Evidence (P)
Representative gypsum mineral material associated with Pakistan
Representative gypsum mineral material: Monoclinic selenite and compact alabaster gypsum from the Salt Range evaporite series.
Representative material specimen. Occurrence does not constitute available inventory. Consignment verification required.

Mandatory Claim Boundary & Sourcing Notice: This page describes mineral/material evidence and buyer requirements. It does not represent current Enigma Earth inventory. Source, ownership, grade, quantity and availability must be verified for the specific enquiry.

GEOLOGICAL APPRAISAL

Mineralogy & Geological Occurrence

Pakistan holds immense geological reserves of high-purity natural gypsum and associated anhydrite. Extensively distributed throughout Punjab, Khyber Pakhtunkhwa, Sindh, and Balochistan, the mineral forms the primary retarder for the national cement manufacturing industry, with high-whiteness deposits supplying plasterboard and agricultural soil conditioning.

Geological Setting & Host Formations

The most extensive deposits occur in the Neoproterozoic Salt Range Formation (associated with halite sequences) and Eocene marine evaporite formations (such as the Bahadur Khel and Kohat gypsum formations). Massive sedimentary gypsum beds also outcrop along the Axial Fold Belt in Balochistan (Spintangi) and southern Indus basin strata in Sindh (Dadu and Thatta).

Key Mineralogy & Chemical Formula

The primary commercial mineral is gypsum (CaSO4·2H2O, containing 20.9% chemically combined water). Anhydrite (CaSO4) naturally occurs interbedded in deeper horizons. Common accessory impurities include calcite, dolomite, clay minerals, quartz, and minor iron oxides.

Formula: Hydrated Calcium Sulfate (CaSO4·2H2O)
PAKISTAN EVIDENCE

Pakistan Evidence & Regional Context

Gypsum extraction is widespread and officially documented across all four provinces. The material is produced from open-cast quarries supplying domestic cement manufacturing plants and regional export terminals.

[P]Official Production Evidence

Salt Range (Mianwali, Dandot, Khewra, Daud Khel)

Pakistan's principal gypsum production belt, yielding high-purity massive white and crystalline gypsum utilized by major cement factories.

Documented Regional Occurrence
Khyber PakhtunkhwaRegional Context

Kohat & Karak Basin (Bahadur Khel, Malgin)

Massive Eocene gypsum sequences with thicknesses exceeding 40 meters, quarried for cement, plaster, and agricultural soil rehabilitation.

Documented Regional Occurrence
BalochistanRegional Context

Spintangi (Sibi) & Chamalang Belts

High-purity sedimentary gypsum beds accessible via railway and highway corridors, serving southern industrial centers.

Documented Regional Occurrence

Dadu, Thatta & Jamshoro Outcrops

Tertiary sedimentary gypsum beds providing raw material feed for southern Sindh cement and plaster industries.

Documented Regional Occurrence
Evidence Boundary: While Pakistan's total gypsum resources are enormous, individual quarry faces vary in chloride content and insoluble silica. Industrial suitability for specific cement or plaster formulations requires lot assay testing.
PRODUCT ARCHITECTURE

Commercial Forms & Processing Stages

Commercial requirements must strictly differentiate between raw extraction, sorted grades, and processed products.

01

Cement-Grade Coarse Lumpy Gypsum

Screened raw gypsum rock crushed to size for intergrinding with Portland cement clinker (typically 3% to 5% by mass) to control initial hydration and flash setting.

Screened lump: 10 mm to 50 mm / 50 mm to 150 mm (CaSO4·2H2O >= 85% - 92%)
02

High-Whiteness Plasterboard & Plaster Grade

Selective pure white alabaster gypsum free of iron staining, calcined into hemihydrate (plaster of Paris / CaSO4·0.5H2O) for gypsum board and dental plaster.

Crushed stone / milled powder (Purity >= 92% - 96%, Whiteness >= 88%)
03

Agricultural Gypsum Soil Conditioner

Finely ground gypsum powder applied to sodic agricultural soils to displace harmful exchangeable sodium with soluble calcium and improve water infiltration.

Agricultural meal: 85% passing 100 mesh (150 microns)
04

Chemical Anhydrite

Anhydrous calcium sulfate (CaSO4) rock with zero structural water, utilized in specialized self-leveling floor screeds and chemical sulfuric acid manufacturing.

Crushed rock: 0 mm to 50 mm (CaSO4 >= 90%)
TECHNICAL QUALIFICATION

Buyer Specification Requirements

Prospective buyers and project owners should specify the parameters below. Values represent typical industrial targets and do not imply universal Pakistani deposit compliance.

Chemical Composition & Purity

5 Parameters
Calcium Sulfate Dihydrate (CaSO4·2H2O)
Grade 1 (High/Plaster): >= 92.0% - 96.0%; Grade 2 (Cement): >= 85.0% - 90.0%; Grade 3: >= 75.0%
Calculated from SO3 and combined water
Sulfur Trioxide (SO3)
High Grade: >= 42.0% - 45.0%; Cement: >= 38.0% - 41.0%
Direct measure of sulfate content
Chemically Combined Water
Typically 18.5% - 20.5% (pure dihydrate = 20.93%)
Differentiates gypsum from anhydrite
Free Moisture (H2O at 45°C)
Target <= 1.0% - 2.5% for lump; <= 0.5% for powder
Critical to prevent clogging in cement plant hoppers
Total Chlorides (as Cl-)
Cement Grade: strictly <= 0.02% - 0.05% (200 - 500 ppm)
Essential to prevent reinforcing steel rebar corrosion

Insolubles & Color Parameters

3 Parameters
Acid-Insoluble Matter (Silica/Silicates)
Target <= 1.5% - 3.5%
Abrasive gangue indicator
Optical Whiteness (ISO)
Plaster Grade: >= 85.0% - 92.0%; Cement: non-critical
HunterLab spectrophotometer
Loss on Ignition (LOI at 1000°C)
Typically 20.0% - 22.0%
Reflects water and minor carbonate evolution

Logistics & Consignment Sizing

3 Parameters
Consignment Tonnage
Road consignments from 500 MT; chartered bulk marine vessels 10,000 - 50,000 MT
Bulk vessel loading at Karachi / Port Qasim
Delivery Basis
Ex-mine stockpile vs FOB Karachi Port / Port Qasim vs CIF destination
Bulk breakbulk or containerized
Testing Standard
ASTM C471M / ASTM C22 / ISO 6331
Independent laboratory test report
VERIFICATION PROTOCOL

Testing & Verification Requirements

Testing and quality verification must be conducted by an appropriate independent laboratory. Commercial transactions require representative sampling, assay, chemical analysis or gemological appraisal, and third-party inspection. Enigma Earth does not maintain a private testing monopoly.

Representative Sampling

Bulk mechanical sampling from conveyor transfer chutes or stratified stockpile increment collection according to ASTM C50 / ISO 3082 standards. Analytical sample preparation by jaw crushing and pulverization.

Standard Test Methods
  • ASTM C22 / C22M (Standard Specification for Gypsum)
  • ASTM C471M (Standard Test Methods for Chemical Analysis of Gypsum and Gypsum Products)
  • ISO 6331 (Determination of calcium, magnesium and sulfate content)
  • EN 196-2 (Methods of testing cement — Chemical analysis of cement and sulfate)
Laboratory Independence

Testing must explicitly differentiate gypsum dihydrate from hemihydrate and anhydrite. Independent laboratories (such as ALS or SGS) provide comprehensive analysis including volatile chlorides.

QUALITY CRITERIA

Impurity Tolerances & Critical Penalty Factors

Commercial specifications require explicit thresholds for penalty elements, structural soundness, color uniformity, and treatment parameters.

Water-Soluble Chlorides (Cl- > 0.05%)

Quality Parameter

Operational Impact: Severe corrosion risk to steel reinforcement bars in concrete structures

Tolerance: International cement manufacturers enforce chloride limits <= 0.02% - 0.04%

Excess Free Moisture (> 3.0%)

Quality Parameter

Operational Impact: Causes adhesive caking, bunker blockages, and feed chute choking in crushing circuits and cement grinding mills

Tolerance: Penalized or rejected above contractual threshold

Free Silica / Quartz (> 4.0%)

Quality Parameter

Operational Impact: Causes abrasive wear on vertical roller mills, ball mill liners, and crushing jaw plates

Tolerance: Preferred < 2.0% for high-speed milling circuits

High Anhydrite Fraction (> 15% in plaster feed)

Quality Parameter

Operational Impact: Alters calcination temperature profiles and retards initial hydration setting times in plasterboard manufacturing

Tolerance: Must be controlled by optical sorting and combined water verification
SUPPLY CHAIN INTEGRITY

Sourcing, Provenance & Preparation Logistics

Due diligence guidelines for legal chain of custody, packaging standards, and maritime export protocols.

Origin Verification & Licensing

Commercial gypsum shipments require provincial mining dispatch challans, royalty payment clearance receipts, and weighbridge certificates from registered quarry concessions.

Quarries operate under provincial Mines & Minerals departments. Sourcing must verify environmental compliance, particularly dust mitigation and sustainable pit rehabilitation.

Provenance Caution: High purity in a grab sample does not ensure that an entire bench or bulk shipment maintains 92%+ purity. Natural sedimentary beds frequently contain interbedded marl ribbons requiring quarry face management.
Packaging & Maritime Transport
  • Unpacked loose bulk cargo loaded into dump trucks, open rail wagons, or bulk carrier vessel holds
  • 1.0 MT to 1.5 MT heavy-duty woven polypropylene bulk bags for containerized export
  • 50 kg multi-wall bags for agricultural and plaster applications

Direct rail haulage or flatbed trucking to national industrial consumers, or direct conveyance to Port Qasim for export bulk vessel loading.

Handling Caution: Milled gypsum powder is hygroscopic and must be protected from atmospheric humidity; coarse lump can be stockpiled outdoors provided drainage is maintained to prevent stormwater pooling.
INQUIRY SUBMISSION GUIDE

What to Send: Technical Requirement Checklist

To evaluate feasibility and structure compliant off-take, please include the following technical details in your enquiry.

1Intended end-use application (Cement retarder vs Plaster of Paris vs Agricultural soil amendment)
2Target purity specification (CaSO4·2H2O % and minimum SO3 %)
3Maximum acceptable limits for free moisture and total chlorides (Cl- ppm)
4Physical sizing distribution (Lump size 10-50 mm / 50-150 mm vs Ground powder)
5Required shipment volume (Trial lot vs Monthly contracted volume vs Shipload parcel)
6Delivery incoterm (Ex-quarry vs FOB Port Qasim vs CIF destination)
7Designated testing laboratory and inspection protocol
Incomplete RFQs lacking grade cutoffs or consignment volumes cannot be processed.
Submit a Gypsum Requirement
FREQUENTLY ASKED QUESTIONS

Frequently Asked Questions: Gypsum & Anhydrite

Key questions regarding Pakistani mineral availability, testing protocols, and trade qualification.

Gypsum acts as a vital set-retarding agent. Without gypsum, tricalcium aluminate (C3A) in the clinker hydrates instantly upon contact with water, causing instantaneous 'flash set'. Gypsum reacts with C3A to form ettringite, controlling the setting time to allow concrete placement and finishing.

Structured Mineral Qualification

Structure a Compliant Gypsum & Anhydrite Requirement

Submit required purity, moisture limits, and consignment tonnages for structured commercial review.