---
title: "Tenacity and hardness of minerals"
subject: "Engineering Geology I"
chapter: 3
key: "semester_3/engineering_geology_i:tenacity-and-hardness-of-minerals"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/tenacity-and-hardness-of-minerals
site: BCT Engineering
---

# Tenacity and hardness of minerals

Engineering Geology I · Chapter 3: Crystallography & Mineralogy

- Asked in: 2079 Bhadra, 2 marks
- Video: [Physical Properties of Minerals Depending on State of Aggregation: Hardness and Tenacity](https://www.youtube.com/watch?v=biSikjs-S_U) — EMPC-IGNOU
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/tenacity-and-hardness-of-minerals
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-3

## Question

Define tenacity and hardness of minerals.

## Short answer

Tenacity is a mineral's resistance to breaking, bending, or cutting; types include brittle, malleable, sectile, flexible, and elastic. Hardness is resistance to scratching, measured on Mohs scale from 1 (talc) to 10 (diamond).

## Answer

**Tenacity** is the resistance of a mineral to breaking, bending, cutting or crushing, that is, how it behaves when force is applied. Types:
- **Brittle**: breaks or powders (quartz, calcite).
- **Malleable**: can be hammered into sheets (gold, copper).
- **Sectile**: can be cut with a knife into shavings (gypsum, talc).
- **Flexible**: bends and stays bent (talc, chlorite).
- **Elastic**: bends and returns to shape (mica).

**Hardness** is the resistance of a mineral to scratching or abrasion. It is measured relatively on the Mohs scale of ten minerals: talc (1), gypsum (2), calcite (3), fluorite (4), apatite (5), orthoclase (6), quartz (7), topaz (8), corundum (9) and diamond (10).

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Tenacity is the mineral's:
   A. Resistance to scratching
   B. Colour of powder
   C. Splitting along planes
   D. Resistance to breaking, bending, cutting or crushing
   Answer: D. Hardness is scratch resistance. (Key point: Tenacity)

2. Malleable minerals such as gold and copper:
   A. Can be hammered into sheets
   B. Break to powder
   C. Bend and return to shape
   D. Bend and stay bent
   Answer: A. Brittle breaks; elastic springs back. (Key point: Malleable)

3. Mica is classified as:
   A. Flexible: bends and stays bent
   B. Elastic: bends and returns to shape
   C. Brittle
   D. Sectile
   Answer: B. Talc and chlorite are flexible, mica is elastic. (Key point: Elastic vs flexible)

## Related in Engineering Geology I

- [Moh's scale of hardness](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Amohs-scale-of-hardness) — Engineering Geology I, chapter 3, asked 14×