3. The FELDSPARS (K,Na,Ca)(Al)Si₃O₈ are an important group of rock forming minerals. They have complex compositions, but most commonly contain potassium (K), sodium, calcium, aluminum, and silica. Feldspar are usually light in color, ranging from pink to white.
     
   1. What elements are in feldspar?

2. Is feldspar harder or softer than quartz? How can you find out?

3. Does feldspar show cleavage? How do you know?

4. TALC is a combination of magnesium, silica, and water. It has the chemical formula Mg₃Si₄ O₁₀(OH)₂ (the OH stands for water in this formula). Talc is very soft , and samples often have a greasy or soapy feel. Talc is used for carving, to make ceramics, in the process of making rubber and of course to make talcum powder!   
     
   1. Is there something that you might put on a baby’s bottom that resembles talc? What is the name of the item?

2. Describe the feel of the mineral.

3. Is talc soft? How can you tell?

5. COPPER (Cu) is an element but also a mineral. Crystals of copper usually occur in malformed and branching groups. Native copper is found in northern Michigan, Bolivia, Arizona, New Mexico, Chile, and Mexico. Native copper is used to obtain copper, but most commercial copper is from other ores.   
     

   1. This is called native copper. Is it a compound or an element?

2. Are there many minerals that are both an element and a mineral? Name some.

3. Describe the color and luster of copper.

4. Where is copper used?