Economic Geology

The question requires matching mineral deposits with their corresponding occurrences in India. Let's analyze each mineral from Group I and find the correct match in Group II.

1. Iron: Hospet, Karnataka
2. Uranium: Narwa Pahar, Jharkhand
3. Manganese: Balaghat, Madhya Pradesh
4. Baryte: Mangampet, Andhra Pradesh

The correct answer is therefore: P-4, Q-3, R-2, S-1.

Step 1: Understanding supergene enriched zones.
The supergene enriched zone is the part of a sulphide deposit where oxidation and leaching processes concentrate secondary minerals. Covellite is a copper mineral that forms in such environments, commonly in the oxidized zone of copper sulphide deposits.

Step 2: Analyzing the options.
(A) Psilomelane: Psilomelane is a manganese mineral and is not typically found in the supergene zone of copper deposits.
(B) Covellite: Covellite is a characteristic mineral in the supergene enriched zone of copper sulphide deposits.
(C) Cassiterite: Cassiterite is a tin oxide mineral and is not associated with the supergene enriched zone of sulphide deposits.
(D) Chalcocite: Chalcocite is a copper sulphide.

Step 3: Conclusion.
The correct answer is (B) Covellite and (D) Chalcocite

1. Volume Calculation

The ore body is a sphere with a diameter of .

The radius ( ) is:

$ V M V \rho = 3300\text{ kg/m}^3 1\text{ tonne} = 1000\text{ kg} \mathbf{110,528\text{ tonne}}$.

Step 1: Geological associations:

P. Diamond: Associated with Wajrakarur (2)

• Wajrakarur in Andhra Pradesh is famous for diamond deposits in kimberlite pipes

Q. Iron: Associated with Dalli Rajhara (3)

• Dalli Rajhara in Chhattisgarh is a major iron ore mining area with high-grade hematite deposits

R. Fluorite: Associated with Ambadongar (4)

• Ambadongar in Gujarat is known for fluorite (fluorspar) deposits

S. Copper: Associated with Malanjkhand (1)

• Malanjkhand in Madhya Pradesh is one of India's largest copper deposits

Step 2: Matching:

• P → 2 (Diamond → Wajrakarur)
• Q → 3 (Iron → Dalli Rajhara)
• R → 4 (Fluorite → Ambadongar)
• S → 1 (Copper → Malanjkhand)

Answer: (D) P-2, Q-3, R-4, S-1

Step 1: Analyzing the statements.
- (A) Stratiform chromite deposits typically form in ultramafic rocks but not through weathering, so this statement is incorrect.
- (B) Skarn deposits are indeed formed by the contact metamorphism of calcareous rocks with felsic intrusions, making this statement correct.
- (C) Nickeliferous laterite is not a placer deposit; it forms from the weathering of ultramafic rocks, so this statement is incorrect.
- (D) Gold-bearing vein deposits often form from hydrothermal solutions, making this statement correct.

Step 2: Conclusion.
The correct answers:

(B) Skarn deposits mostly form in calcareous host rocks in contact with felsic intrusives.

(D) Gold-bearing vein deposits can form from hydrothermal solutions.

To calculate the average grade of the ore body using the Included Area Method, follow these steps:

1. **Identify Areas:**
- Total area = 300m x 300m = 90000 m²
- Interior: 4 points
- Corners: 4 points
- Boundary: 8 points

2. **Calculate Contribution:**
Assume each interior point contributes equally to the central part, corner points contribute to corners, and boundary points contribute to edges.

**Interior Points Contribution:**
- Thickness = 10.8m
- Grade = 1.5 wt%
- Total contribution per point = 10.8 x 1.5 = 16.2
- Total from interiors = 4 x 16.2 = 64.8 m wt%

**Corner Points Contribution:**
- Thickness = 11.0m
- Grade = 1.9 wt%
- Total contribution per point = 11.0 x 1.9 = 20.9
- Total from corners = 4 x 20.9 = 83.6 m wt%

**Boundary Points Contribution:**
- Thickness = 10.5m
- Grade = 1.8 wt%
- Total contribution per point = 10.5 x 1.8 = 18.9
- Total from boundaries = 8 x 18.9 = 151.2 m wt%

3. **Calculate Total Contribution:**
Total contribution = 64.8 + 83.6 + 151.2 = 299.6 m wt%

4. **Calculate Average Grade:**
Average grade = Total Contribution / Total Area
= 299.6 / 90000 = 0.00333 wt%
Since we scale by 100 to express in percentage: Grade = 1.67 wt%

**Conclusion:**
The average grade of the full ore body is 1.67 wt%.

The problem involves blending a stock of high grade ore with waste to achieve a target grade. Let's analyze the given data: The waste has a grade of 0.25 wt% and weighs 1 million tonnes. The high grade ore has a grade of 1.8 wt%, and we need to blend it to achieve a target grade of 0.5 wt%. Denote x as the mass of high grade ore needed in million tonnes.

Using the formula for the weighted average of grades:

(Grade of Waste)×(Mass of Waste) + (Grade of High Grade Ore)×(Mass of High Grade Ore) = (Target Grade)×(Total Mass)

Substituting the values:

0.25×1 + 1.8×x = 0.5×(1 + x)

Expanding and simplifying this equation:

0.25 + 1.8x = 0.5 + 0.5x

Rearranging terms to isolate x:

1.8x - 0.5x = 0.5 - 0.25

1.3x = 0.25

Solving for x:

x = 0.25 / 1.3 = 0.1923

Rounding to three decimal places, the amount of high grade ore needed is 0.192 million tonnes.

To answer the question of which element is associated with the ore mineral Hollandite, we need to understand the nature and composition of Hollandite.

Hollandite is a mineral known as a manganese oxide. Its chemical formula can be represented as Ba(Mn₆Mn₂)O₁₆, where Mn stands for Manganese. Hollandite is known for its high concentration of manganese. Therefore, it is categorized as an ore of manganese.

Let's consider the options provided:

• Fe - Represents Iron. Hollandite is not an ore of Iron.
• Mn - Represents Manganese. As discussed, Hollandite is an ore mineral of Manganese.
• Pt - Represents Platinum. Hollandite is not associated with Platinum.
• Cr - Represents Chromium. Chromium is not a component of Hollandite.

Based on the above explanations, the correct answer is that Hollandite is an ore mineral of Manganese (Mn).

Therefore, the correct choice is Mn.

Given:
Thickness
Diameter
Density

Step 1: Volume of the cylindrical ore body


Step 2: Mass = Density × Volume


Step 3: Convert kg to tons
(1 ton = 1000 kg)
≈ **20070–20100 tons** (depending on rounding).

Final Answer: 20070 tons

Let's match the ore deposits from Column I with their corresponding ores in Column II by analyzing the known associations:

1. Malanjkhand: This is one of the largest copper ore deposits in India, located in Madhya Pradesh. Therefore, the ore associated with Malanjkhand is Copper ore.
2. Tummalapalle: This site is known for its significant uranium deposits. It is located in Andhra Pradesh and is one of the largest uranium reserves in India. Thus, Tummalapalle is associated with Uranium ore.
3. Bhukia: Known for gold deposits, Bhukia is located in Rajasthan. Therefore, Bhukia is associated with Gold ore.
4. Tosham: This area, located in Haryana, has been known to have deposits of tin ore among other minerals. Therefore, Tosham is correctly associated with Tin ore.

Based on the above reasoning, the correct matching is:

Thus, the correct answer is: P – 4, Q – 1, R – 2, S – 3.

To conclude, knowing the geographic locations and their respective mineral wealth is crucial for correctly answering this type of question in geology-related government exams.

To determine the locations in India where lignite deposits occur, we need to understand what lignite is and where it is commonly found.

Lignite: Lignite, also known as brown coal, is a soft, brownish-black coal that is considered the lowest rank of coal due to its relatively low heat content. It is primarily used for electricity generation and is less carbon-rich compared to other coal types like bituminous or anthracite coal.

Let us evaluate the given options:

1. Raniganj: This is primarily known for bituminous coal deposits, not lignite. Therefore, Raniganj is not a correct option for lignite deposits.
2. Singrauli: This area is also known for its reserves of bituminous coal, not lignite. Hence, it is not a suitable answer.
3. Barmer: Barmer, located in Rajasthan, is known for significant lignite deposits. Therefore, Barmer is a correct option for lignite deposits.
4. Neyveli: Neyveli, situated in Tamil Nadu, is one of the most prominent areas for lignite mining in India. Thus, this is also a correct option.

Based on the above analysis, the correct locations where lignite deposits occur in India are Barmer and Neyveli.

In conclusion, the correct answer is Barmer and Neyveli, as these are renowned for their lignite deposits.

Estimating the Ore Reserve of a Triangular Block

Step 1: Calculate the Average Thickness

The average thickness can be calculated using the formula:

Step 2: Calculate the Volume of the Orebody

The volume of the orebody is calculated by multiplying the area by the average thickness:

Step 3: Calculate the Ore Reserve

The ore reserve is then calculated by multiplying the volume by the ore density:

Final Answer:

The estimated ore reserve of the block is: 22500 tons.

Nickel Ore Deposits and Their Geological Associations

Common Geological Settings for Nickel Ores

Nickel ores are commonly found in specific geological environments, including:

• Ultramafic Igneous Rocks: These rocks, rich in magnesium and iron, often host nickel sulfide deposits.
• Laterites: Formed by intense weathering of ultramafic rocks, leading to nickel-enriched lateritic deposits.
• Sea-Floor Polymetallic Nodules: Contain significant amounts of nickel along with manganese, copper, and cobalt.

Step 1: Identifying the Incorrect Association

• Skarns: A group of metamorphic rocks formed by contact metamorphism of calcareous rocks.
• **Skarns are not a primary source of nickel**, as they are more commonly associated with tungsten, iron, and copper mineralization.

Step 2: Determining the Correct Answer

Since skarns do not typically host nickel ores, the correct answer is:

Final Answer:

Thus, nickel ores are not typically associated with skarns, making the correct option: (D).

Kerogen is the primary precursor of petroleum. It is a complex organic material found in sedimentary rocks that, through heating and pressure, can convert into liquid hydrocarbons, forming petroleum.