The ore mined from the earth contains some unwanted substances called gangue. Enrichment of ore is done by various methods depending upon the nature of the impurities. Hydraulic washing is the process based on the difference in densities of ore and gangue particles. Froth floatation method is used for ores with different wetting properties of ore and gangue particles. On adding sulphide ore in a mixture of oil and water, the sulphide particles are wetted by oil and gangue particles are wetted by water. On passing air in this mixture, sulphide ore particles form light oily froth and reach the surface whereas gangue particles settle down at the bottom. Few ores are enriched by chemical processes.
The rocky and silica matter associated with an ore is called

Options

A. slag
B. mineral
C. gangue
D. flux.

Answer

To answer the question regarding the rocky and silica matter associated with an ore, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ore**: An ore is a naturally occurring solid material from which a metal or valuable mineral can be extracted. However, ores often contain impurities that need to be removed to obtain the desired metal.

2. **Identifying Impurities**: The impurities present in the ore can include rocky materials and silica. These unwanted substances are not part of the desired metal and can hinder the extraction process.

3. **Defining Gangue**: The term used to describe the rocky and silica matter associated with an ore is called **gangue**. Gangue consists of the non-valuable minerals that are extracted along with the ore.

4. **Importance of Removing Gangue**: The removal of gangue is crucial for the enrichment of the ore, which enhances the concentration of the desired metal and makes the extraction process more efficient.

5. **Conclusion**: Therefore, the rocky and silica matter associated with an ore is referred to as **gangue**.

### Final Answer:
The rocky and silica matter associated with an ore is called **gangue**.

---