Density of Sand Lab Objective: Compare the density of Hawaiian green sand to NJ sand.

Where does sand come from? What is sand? Hawaii: Black Sand Beach Hawaii: Green Sand Beach NJ: Sand Beach Sand is made from rock that has been weathered and broken down to sediment or mineral grains. Streams and rivers transport sediment from inland to sea.

Dense rocks/sand have minerals composed of “heavy” elements Elements Iron Magnesium Calcium Minerals Olivine Amphiboles Ca feldspars These minerals are dark in color and heavy (dense) They are common in ocean crust & mantle make

“Light” Rocks/Sand have a high silica content.  Silica or Silicates are a mineral group made of silicon & oxygen (“light” elements)  Silicate rocks make up most of Earth’s continental crust.  SiO 2 - also known as Quartz Silica minerals are “light”

~ 50 % silica in rocks - High in heavy and dense iron & magnesium minerals - Dark color: black/gray/green - Green mineral = olivine; common in mantle. Hawaiian volcanoes have a deep magma source. Hawaii sand is mostly made of Basalt Rock (Rock of OCEAN CRUST )

NJ sand is made from rocks of Continental Crust Felsic > 70% silica Light colored minerals Less dense.

Oceanic Crust is denser than Continental Crust. Result: Subduction When ocean crust and continental crust collide; oceanic crust sinks back into the mantle. It’s heavier! This creates volcanoes on edges of some continents. (Ring of Fire) Subduction:

Hawaii vs. NJ Hawaii: Volcanic island in the middle of the Pacific Ocean. Formed over a “hot spot” where magma comes from deep with Earth. Rocks made of basaltic oceanic crust. Basalt = less silica; more heavy dark minerals with iron and magnesium NJ: Continental Crust Silica-rich minerals in rock; light in color and density Not volcanic

Hawaii v. NJ