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Question

Difficulty: EasyRocks, Minerals, and Soil

A geologist rubs an unknown mineral specimen across an unglazed porcelain plate to observe the color of the powdered residue left behind. Which physical property of the mineral is being tested?

  1. A
    Luster
  2. StreakAnswer
  3. C
    Hardness
  4. D
    Cleavage

Answer

Streak is the physical property determined by rubbing a mineral against an unglazed porcelain plate to observe its powdered mark.
Streak is the true color of a mineral in its powdered form, produced by scraping the specimen across an unglazed porcelain streak plate. Unlike external color, which can vary significantly due to weathering or chemical impurities, a mineral's streak is generally constant and serves as a reliable identification property.

Step-by-Step Solution

1
Identify the diagnostic testing procedure described in the scenario.
Rubbing a mineral sample against an unglazed porcelain plate scrapes off a fine line of powdered mineral residue.
Diagnostic mineral tests evaluate specific physical and optical characteristics.
2
Match the observed powdered residue to its scientific property.
The color of a mineral's powder left on a porcelain plate is defined as its streak.
Streak provides a more consistent diagnostic indicator than surface color because it is less affected by surface impurities.

Key Concept

Mineral Identification through Physical Properties (Streak Test)
Estimated Time:35s
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Topics

Rocks, Minerals, and Soil

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