Metals like gold, silver, and platinum are known as **precious minerals**. Let's understand why this is the correct answer.

**Ferrous minerals**:
- Ferrous minerals are those that contain iron as their main component, such as iron ore and manganese.
- Gold, silver, and platinum do not contain iron as their main component, so they cannot be classified as ferrous minerals.
- Therefore, option 'A' is incorrect.

**Non-ferrous minerals**:
- Non-ferrous minerals are those that do not contain iron as their main component.
- Gold, silver, and platinum fall under this category as they do not contain iron.
- However, not all non-ferrous minerals are precious. There are other non-ferrous minerals like copper, zinc, aluminum, etc. that are not classified as precious minerals.
- Therefore, option 'B' is incorrect.

**Non-metallic minerals**:
- Non-metallic minerals are those that do not contain metals.
- Gold, silver, and platinum are metals, so they cannot be classified as non-metallic minerals.
- Therefore, option 'C' is incorrect.

**Precious minerals**:
- Precious minerals are rare and valuable minerals that are highly sought after for their beauty, rarity, and economic value.
- Gold, silver, and platinum are considered precious minerals due to their aesthetic appeal, durability, and use in various industries such as jewelry, electronics, and chemical catalysts.
- These minerals are often associated with luxury and have a high market value.
- Therefore, option 'D' is the correct answer.

In conclusion, metals like gold, silver, and platinum are classified as precious minerals because of their rarity, value, and wide range of applications.