In mineralogy and gemstone chemistry, turquoise is an ornamental ore or mineral that serves as a source of which metal?

Introduction / Context:
Turquoise is a well known blue to green ornamental stone used in jewellery and decorative objects for thousands of years. In addition to its aesthetic value, it is also a mineral containing certain metals in its structure. Questions in general chemistry and geology often ask you to identify which metal is associated with a particular coloured mineral. This question focuses on turquoise and asks which metal it can be considered an ore or mineral of.

Given Data / Assumptions:

• The mineral mentioned is turquoise, a blue-green ornamental stone.
• The options are metals: copper, manganese, mercury, and tin.
• Turquoise is known to contain metallic elements in its chemical formula.
• We assume standard textbook information about turquoise as a copper containing phosphate mineral.

Concept / Approach:
Turquoise is a hydrated phosphate of copper and aluminium, typically represented by a formula such as CuAl6(PO4)4(OH)8·4H2O. The characteristic blue to green colour of turquoise is largely due to the presence of copper ions in its structure. Although aluminium is also present, in ore classification and exam oriented questions turquoise is commonly described as a copper bearing mineral. Manganese, mercury, and tin have other common ores and are not primarily associated with turquoise in basic geology or chemistry references.

Step-by-Step Solution:
Step 1: Recall the colour and composition of turquoise. Turquoise is typically blue or blue-green, indicating the presence of copper. Step 2: Connect colour with metal content. Many blue and green minerals, such as malachite and azurite, owe their colour to copper, and turquoise is no exception. Step 3: Consider the chemical formula. Turquoise includes Cu (copper) and Al (aluminium) along with phosphate groups and water. Step 4: Match this with the options and select copper as the metal of which turquoise is an ore or mineral.

Verification / Alternative check:
Lists of coloured minerals in introductory geology and chemistry materials often describe turquoise as a hydrous phosphate of copper and aluminium. When classifying ores, copper is associated with several minerals like chalcopyrite, malachite, azurite, and turquoise. Manganese is more typically sourced from minerals like pyrolusite, mercury from cinnabar, and tin from cassiterite. Turquoise is not cited as an important ore for these latter metals. This pattern confirms that turquoise is a copper bearing mineral and is considered an ore of copper in simple exam questions.

Why Other Options Are Wrong:
Option B (Manganese): Common manganese ores include pyrolusite and psilomelane; turquoise is not listed among them. Option C (Mercury): Mercury is primarily obtained from cinnabar (HgS); turquoise does not contain mercury. Option D (Tin): Tin is usually extracted from cassiterite (SnO2), not from turquoise.

Common Pitfalls:
Students may be tempted to guess based on random association with colour or confuse turquoise with other green minerals like malachite, which is also a copper ore. While several metals can colour minerals, copper is particularly famous for producing vivid blue and green hues in gemstones and ores. A useful memory trick is to associate turquoise jewellery with other blue copper minerals like azurite; this helps reinforce the idea that turquoise is a copper containing mineral.

Final Answer:
Turquoise is an ore or mineral of Copper.