Cara Menentukan 3 Jenis Batuan (Beku,Sedimen dan Metamorf) bersama Pak Kristiawan Widiyanto, LIPI

Introduction

In this tutorial, we will explore how to identify the three main types of rocks: igneous, sedimentary, and metamorphic. Understanding these classifications is essential for geology enthusiasts and students alike. This guide will provide you with clear methods to identify each rock type based on their characteristics.

Step 1: Identifying Igneous Rocks

Igneous rocks form from the cooling and solidification of magma or lava. Here’s how to identify them:

• Texture: Look for a granular texture. Igneous rocks can be:
  • Coarse-grained (e.g., granite) if they cooled slowly underground.
  • Fine-grained (e.g., basalt) if they cooled quickly on the surface.
• Color: Note the color variations:
  • Light-colored rocks typically contain quartz and feldspar (e.g., granite).
  • Dark-colored rocks may have more iron and magnesium, like basalt.
• Common Examples: Familiarize yourself with common igneous rocks such as:
  • Granite
  • Basalt
  • Pumice

Step 2: Identifying Sedimentary Rocks

Sedimentary rocks are formed from the accumulation of sediments. To identify them, consider the following:

• Layering: Look for distinct layers or strata, which indicate sediment deposition over time.
• Fossils: Check for fossilized remains of plants or animals, often found in sedimentary rocks.
• Composition: Sedimentary rocks can be:
  • Clastic (formed from fragments of other rocks, e.g., sandstone).
  • Chemical (formed from precipitation of minerals, e.g., limestone).
  • Organic (formed from the remains of living organisms, e.g., coal).
• Common Examples: Recognize examples like:
  • Sandstone
  • Shale
  • Limestone

Step 3: Identifying Metamorphic Rocks

Metamorphic rocks arise from existing rocks that have undergone changes due to heat, pressure, or chemically active fluids. Here’s how to identify them:

• Foliation: Observe for banding or layering. This is a key feature of many metamorphic rocks.
• Texture: Check for a crystalline or glassy texture resulting from the recrystallization of minerals.
• Parent Rock: Identify the original rock type:
  • Igneous parent rocks can become metamorphic rocks like granite to gneiss.
  • Sedimentary parent rocks can transform into schist or marble.
• Common Examples: Learn about typical metamorphic rocks such as:
  • Schist
  • Gneiss
  • Marble

Conclusion

In summary, identifying rock types involves observing textures, colors, layering, and the presence of fossils or foliation. By following these steps, you can effectively classify rocks into igneous, sedimentary, or metamorphic categories. As you continue your geological exploration, consider collecting samples and practicing your identification skills in the field for hands-on experience.