The type of rock mineral that sparkles is known as quartz. Quartz can have a variety of sparkly appearances due to the presence of inclusions or internal structures that reflect and refract light. This sparkling effect is often referred to as "druzy" or "sparkly quartz" and is commonly used in jewelry and decorative items for its beautiful and eye-catching appearance. **

As a manga artist, you can use a variety of pens for highlights and sparkles, but one popular choice is a white gel pen. White gel pens are great for adding highlights and sparkles to your artwork because they can easily be applied over darker ink and provide a bright, opaque finish. They are also versatile and can be used on various surfaces, such as paper and plastic, making them a great tool for adding details to your manga illustrations. **

As a manga artist, you may want to consider using gel pens or metallic markers for highlights and sparkles in your artwork. Gel pens provide a smooth and consistent flow of ink, making it easy to create precise and detailed highlights. Metallic markers can add a shiny and eye-catching effect to your drawings, perfect for creating sparkles and other special effects. Experiment with different pens to find the ones that work best for your style and desired effects. **

No, the luminous clock is not radioactive. The luminescence in the clock is typically achieved using a phosphorescent material that absorbs light and then slowly releases it over time. This process does not involve any radioactive materials. The glow from the clock is simply a result of this light-absorption and emission process. **

Self-luminous bodies are objects that emit their own light, as opposed to reflecting light from another source. Examples of self-luminous bodies include stars, the sun, and certain types of light bulbs. These objects generate their own energy through processes like nuclear fusion or electrical current, which produces light as a byproduct. **

A luminous point is a theoretical concept used in physics and optics to represent a source of light that emits light in all directions. It is often used as a simplification in the study of light and its behavior, allowing for easier calculations and analysis. In reality, a luminous point does not exist as a physical object, but it is a useful tool for understanding the behavior of light in various systems. **

The luminous intensity is specified for reflector lamps because it measures the amount of light emitted in a specific direction, which is important for directional lighting applications such as spotlights and floodlights. Reflectors are designed to control and direct light in a specific direction, so specifying luminous intensity helps to ensure that the lamp is suitable for its intended purpose. Luminous flux, on the other hand, measures the total amount of visible light emitted by a source in all directions, which may not be as relevant for reflector lamps where the focus is on directing light in a specific direction. **

In physics, a self-luminous object is one that produces its own light, such as the sun or a light bulb. These objects emit light due to internal processes, such as nuclear fusion or electrical excitation. On the other hand, an externally luminous object is one that reflects light from another source, such as the moon or a mirror. These objects do not produce their own light but appear illuminated due to the light they reflect from another source. **