Black Jack is

Options

A. Silicate ore
B. Oxide ore
C. Carbonate ore
D. Sulphide ore

Explanation

To solve the question "Black Jack is", we need to identify which type of ore is referred to as "blackjack" among the given options: silicate ore, oxide ore, carbonate ore, and sulphide ore.

### Step-by-Step Solution:

1. **Understanding the Term "Blackjack":**
- The term "blackjack" refers to a specific type of ore that is characterized by its black appearance.

2. **Identifying the Color of Ores:**
- We need to analyze which of the given ore types typically has a black color. The options provided are:
- Silicate ore
- Oxide ore
- Carbonate ore
- Sulphide ore

3. **Recognizing Black Ores:**
- Among the listed ores, sulphide ores are known to commonly appear black. This is an important clue to identify blackjack.

4. **Specific Examples of Blackjack:**
- Blackjack is specifically identified as zinc blend ore, which is a sulfide ore of zinc. The chemical formula for zinc blend is ZnS (zinc sulfide).
- Other examples of black ores include Cu2S (copper(I) sulfide) and FeS (iron(II) sulfide), which also exhibit a black color.

5. **Conclusion:**
- Based on the analysis, we conclude that blackjack refers to a sulphide ore. Therefore, the correct answer is option D, which corresponds to sulphide ore.

### Final Answer:
Blackjack is a sulphide ore (Option D).

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