Igneous Rock is formed when a magma cools underground and crystallizes or when it erupts unto the surface of the ground, cools and crystallizes. Magma that erupts onto the surface is called lava. When magma cools slowly underground the crystals are large enough to see.
Readings for compression tests usually vary between 175 to 250 PSI (Pounds per Square Inch). A higher reading generally indicates better engine performance; however you should check your vehicle manual to find out what the ideal reading should be for your vehicle.
A faulty oxygen sensor will cause you to fail an emissions test. A brand new replacement oxygen sensor can cost you from $20 to $100, depending on the make and year of your car. Taking your car to a mechanic to fix the issue can cost up to $200. Though, this depends on the type of car and the rates of the mechanic.