Granite — Complete Guide
Granite is a coarse-grained igneous rock formed by the slow crystallisation of molten magma deep beneath the earth’s surface. It is one of the hardest, densest and most durable natural building stones, prized for its strength, low water absorption, polish-retention, and rich variety of colours and patterns.
India is the world’s second-largest producer of granite. Indian granites are mined in Karnataka, Andhra Pradesh, Telangana, Tamil Nadu, Rajasthan and Jharkhand — and exported to over 100 countries. Granite is governed by IS 1124, IS 3316 and IS 14223.
What is Granite?
Granite is a felsic, plutonic igneous rock composed primarily of quartz (20–60%), feldspar (35–65%), and minor amounts of mica (biotite or muscovite) and amphibole. The interlocking crystalline texture gives granite its characteristic strength and resistance to wear.
Granite is rated 6–7 on the Mohs hardness scale, making it harder than most steels and second only to diamond, corundum and topaz among commonly available stones.
Mineral Composition
| Mineral | Percentage | Role |
|---|
| Quartz | 20 – 60% | Hardness, abrasion resistance |
| Feldspar (Orthoclase/Plagioclase) | 35 – 65% | Colour, body |
| Mica (Biotite, Muscovite) | 5 – 15% | Sheen / sparkle |
| Amphibole / Hornblende | 0 – 10% | Dark spots, toughness |
| Accessory minerals | < 5% | Magnetite, zircon, apatite etc. |
Popular Indian Granite Types
| Colour Family | Examples | Origin |
|---|
| Black | Absolute Black, Black Galaxy, Jet Black | Andhra, Karnataka |
| Red | Lakha Red, Imperial Red, Multi Red | Rajasthan, Tamil Nadu |
| Pink | Pink Salmon, Raw Silk, Rosy Pink | Karnataka, Tamil Nadu |
| White / Grey | Kashmir White, P White, Steel Grey | Andhra, Karnataka |
| Brown / Tan | Tan Brown, Coffee Brown, Sapphire Brown | Andhra, Karnataka |
| Green | Hassan Green, Forest Green, Verde Marina | Karnataka |
| Blue | Vizag Blue, Lavender Blue | Andhra Pradesh |
Standard Sizes & Forms
| Form | Typical Size | Thickness |
|---|
| Slab (Gangsaw) | 2.6 – 3.2 m x 1.6 – 1.9 m | 15 / 18 / 20 / 30 mm |
| Slab (Cutter) | 1.5 – 2.2 m x 0.6 – 0.9 m | 15 / 18 / 20 mm |
| Tiles | 305 x 305 / 305 x 610 / 600 x 600 mm | 10 / 12 mm |
| Cut to Size | Customised | 15 – 30 mm |
| Kerb / Block | Project-specific | 50 – 150 mm |
Physical & Mechanical Properties
| Property | Typical Value |
|---|
| Density | 2,600 – 2,800 kg/m³ |
| Compressive Strength | 100 – 250 MPa |
| Flexural / Modulus of Rupture | 10 – 25 MPa |
| Water Absorption (24 hr) | < 0.5% |
| Mohs Hardness | 6 – 7 |
| Abrasion Resistance | Very High |
| Polish-Retention | Excellent (90 – 95 gloss units) |
| Thermal Conductivity | 2.5 – 3.5 W/m.K |
| Coefficient of Thermal Expansion | 5 – 8 x 10⁻⁶ /°C |
| Frost Resistance | Excellent |
Surface Finishes
- Polished: Mirror-like gloss, brings out colour, easy to clean
- Honed: Smooth matt finish, low reflection, anti-slip
- Flamed (Thermal): Rough textured for outdoor flooring, anti-skid
- Leathered: Soft pebble texture, hides fingerprints
- Brushed: Worn-look antique finish
- Bush-hammered: Coarsely textured for paving
- Sandblasted: Uniformly rough surface
- Sawn / Rough: As-cut for cladding and rough work
Quarrying & Processing
- Prospecting & Lease: Geological survey, mining lease
- Block Extraction: Wire-saw / diamond-wire cutting to extract large blocks (3 x 2 x 2 m)
- Block Dressing: Trimming, squaring at quarry
- Transport: Trucks / cranes to processing factory
- Slab Cutting: Gangsaw or block-cutter machines slice block into slabs (15–30 mm)
- Polishing: Multi-head polishing lines with abrasive disks
- Cutting / Trimming: Sizing, edge profiling
- Quality Check & Packing: A-frame, wooden crate dispatch
Tests on Granite
- Compressive Strength Test — IS 1121 (Part 1)
- Flexural Strength Test — IS 1121 (Part 2)
- Water Absorption & Bulk Density — IS 1124
- Abrasion Resistance — IS 1706
- Mohs Hardness Test
- Modulus of Rupture — IS 14223 (Part 1)
- Petrographic / Mineralogical Examination
- Frost / Weathering Resistance — IS 1126
- Acid & Stain Resistance
- Resonance / Soundness (tap test)
Granite vs Marble — Comparison
| Parameter | Granite | Marble |
|---|
| Rock Type | Igneous | Metamorphic (limestone origin) |
| Mohs Hardness | 6 – 7 | 3 – 4 |
| Density | 2,600 – 2,800 kg/m³ | 2,500 – 2,700 kg/m³ |
| Compressive Strength | 100 – 250 MPa | 70 – 140 MPa |
| Water Absorption | < 0.5% | 0.2 – 0.6% |
| Acid Resistance | Excellent | Poor (etches) |
| Heat Resistance | High | Moderate |
| Look | Speckled / crystalline | Veined / smooth |
| Typical Use | Flooring, kitchens, facade, outdoor | Flooring, walls, decorative |
| Cost (slab, Rs/sqft) | 80 – 350 | 90 – 1,200 |
Uses of Granite
- Kitchen countertops and platforms
- Flooring (residential, commercial, airports, malls)
- Staircase treads and risers
- External cladding and facade
- Wall panelling and feature walls
- Sills, jambs, copings and parapets
- Building columns and pillars
- Memorial stones, tombstones and statues
- Bridges, kerbs and paving blocks
- Industrial flooring (where chemical/abrasion resistance needed)
- Bathrooms (vanity tops, shower walls)
- Garden landscaping — benches, water features
Advantages
- Extremely hard and durable — 100+ years lifespan
- Very low water absorption — stain resistant when sealed
- Resistant to scratches, chips and abrasion
- Heat resistant — hot pans don’t damage surface
- Acid and chemical resistant (unlike marble)
- Excellent polish retention
- Wide variety of colours, patterns and finishes
- Adds luxury and resale value to property
- Hygienic — non-porous when sealed
- UV stable — doesn’t fade outdoors
- Locally available in India at competitive prices
- Reusable / recyclable
Disadvantages
- Heavy — requires strong substrate and proper handling
- Brittle at edges — chipping possible during transport
- Higher initial cost than ceramic / vitrified tiles
- Requires periodic sealing (every 1–3 years) for porous varieties
- Cold to walk on in winter
- Slippery when wet (if polished finish used outdoors)
- Joints can collect dirt if not properly grouted
- Natural variation — no two slabs are identical
- Skilled labour required for cutting and installation
- Difficult to repair if cracked
Quantity Estimation & Wastage
For granite slab work, estimate based on net area + wastage:
| Application | Wastage Allowance |
|---|
| Plain floor (simple cuts) | 5 – 8% |
| Countertops (with sink / hob cut-outs) | 15 – 25% |
| Staircase (treads + risers + skirting) | 10 – 15% |
| Cladding | 10 – 12% |
| Curved / complex shapes | 20 – 30% |
Required Slab Area = Net Surface Area × (1 + Wastage %)
Best Practices for Installation
- Check slab for cracks, patches and colour match before installation
- Use 1:4 cement-sand mortar bed (20–25 mm thick) for flooring
- Apply polymer-modified adhesive for cladding above 1.5 m height
- Mechanical anchors (cramps, dowels) for facade above 2 storeys
- Maintain uniform 2–3 mm joints filled with epoxy / colour-matched grout
- Seal porous granites every 1–3 years with penetrating sealer
- Avoid acid-based cleaners; use pH-neutral stone cleaner
- Use lifting clamps / suction pads for slab handling
- Provide expansion joints every 6–8 m for large floors
- Cure mortar bed for at least 7 days before opening for traffic
Cost (Approximate, Indian Market)
| Granite Type | Rate (Rs / sqft) |
|---|
| Economy — P White, Sadarahalli | 50 – 90 |
| Mid-range — Tan Brown, Steel Grey | 90 – 160 |
| Premium — Black Galaxy, Imperial Red | 180 – 350 |
| Exotic / Designer (Vizag Blue, Forest Green) | 300 – 800 |
| Installation labour | 40 – 80 / sqft |
| Polishing (on site) | 25 – 50 / sqft |
Applicable Standards
| Standard | Description |
|---|
| IS 1124 | Method of test for determination of water absorption, apparent specific gravity and porosity of natural building stones |
| IS 1121 (Parts 1–4) | Methods of test for determination of strength properties of natural building stones |
| IS 14223 (Part 1) | Polished building stones — Granite — Specification |
| IS 3316 | Structural granite — Specification |
| IS 1706 | Method for determination of resistance to wear by abrasion of natural building stones |
| IS 1126 | Method of test for determination of durability of natural building stones |
| IS 4101 (Part 1) | Code of practice for external facing and veneering — stone facing |
Conclusion
Granite is the gold standard for hard, durable natural stone in construction. With compressive strength up to 250 MPa, near-zero water absorption, and lifespan exceeding 100 years, it justifies its price in any application demanding longevity and elegance — kitchen tops, public flooring, facade cladding or monuments.
For Indian projects, always specify IS 14223 / IS 3316 grade granite, check the slab in daylight for hairline cracks, and ensure proper sealing where indicated. Compared with marble or kota stone, granite is the toughest of the three and the right choice wherever heavy use, water exposure or chemical contact is expected.